Flame-retardant polyurethane soft foam based on phenylphosphonic acid intercalated kaolin as well as preparation method and application of flame-retardant polyurethane soft foam

Abstract

The invention relates to the technical field of flame-retardant materials, in particular to flame-retardant polyurethane soft foam based on phenylphosphonic acid intercalated kaolin as well as a preparation method and application of the flame-retardant polyurethane soft foam. Preparing potassium acetate intercalated kaolin; preparing phenylphosphonic acid intercalated kaolin; the preparation method comprises the following steps: adding phenylphosphonic acid intercalated kaolin into a chitosan aqueous solution, immersing polyurethane foam, continuously and slowly stirring, taking out and drying after immersing, then immersing in a glutaraldehyde ethanol solution, stirring, taking out and drying to obtain the flame-retardant polyurethane soft foam. By adopting the steps, the prepared chitosan-coated phenylphosphonic acid intercalated kaolin coating has low heat release rate and smoke release rate, and also has excellent flame retardant property; the chitosan-coated phenylphosphonic acid intercalated kaolin coating and the flame-retardant polyurethane soft foam can significantly reduce the combustible gas release and smoke generation rate under a thermal exposure condition.

Description

Technical Field

[0001] This invention relates to the field of flame retardant materials technology, and in particular to a flame retardant polyurethane soft foam based on phenylphosphonic acid intercalated kaolin, its preparation method and application. Background Technology

[0002] Coal-series kaolin is a solid waste generated during coal mining and washing. Its main component is kaolin, with small amounts of coal and inorganic minerals. While its carbon content and calorific value are low, its reserves are enormous. Long-term accumulation occupies land, causing environmental pollution problems that need to be addressed. In recent years, coal gangue has been increasingly utilized for resource recovery, including power generation, brick making, road paving, mine backfilling, and the extraction of useful minerals. By calcining coal-series kaolin and adding it to the production processes of coatings and papermaking, not only can environmental pollution be reduced, but economic value can also be created, promoting the development of a circular economy.

[0003] Kaolin can be used as an important filler in flame-retardant coatings due to its multiple advantages, including physical barrier effects, its ability to improve the overall performance of coatings as a general-purpose filler, wide availability, and low cost. It can serve as a highly efficient synergistic flame retardant to enhance system performance, while also fulfilling the basic filler function of coatings, playing an indispensable role in the development of high-performance, environmentally friendly flame-retardant coatings. Modification of kaolin (such as calcination, surface modification, and intercalation) can further improve its dispersibility and flame-retardant efficiency in flame-retardant coatings. Summary of the Invention

[0004] The purpose of this invention is to provide a flame-retardant polyurethane soft foam based on phenylphosphonic acid intercalated kaolin, its preparation method and application. The prepared chitosan-encapsulated phenylphosphonic acid intercalated kaolin coating has a low heat release rate and smoke release rate, while also exhibiting excellent flame-retardant properties.

[0005] To achieve the above objectives, this invention provides a method for preparing flame-retardant polyurethane flexible foam based on phenylphosphonic acid intercalated kaolin, comprising the following steps: S1. Add kaolin powder to dimethyl sulfoxide and water, perform intercalation treatment under magnetic stirring, and obtain DMSO intercalated kaolin after centrifugation and drying. S2. Add the DMSO-intercalated kaolin obtained in S1 to a potassium acetate aqueous solution, perform displacement intercalation treatment under magnetic stirring, and obtain potassium acetate-intercalated kaolin after centrifugation and drying. S3. Add the potassium acetate intercalated kaolin from S2 to a phenylphosphonic acid aqueous solution, perform displacement intercalation treatment under magnetic stirring, and obtain phenylphosphonic acid intercalated kaolin after centrifugation and drying. S4. Add the phenylphosphonic acid intercalated kaolin obtained in S3 to the chitosan aqueous solution, mix under magnetic stirring, immerse in polyurethane foam and continue to stir slowly, remove and dry after soaking to obtain intermediate polyurethane foam. S5. Immerse the intermediate polyurethane foam from S4 in a glutaraldehyde ethanol solution and stir. Remove and dry to obtain flame-retardant polyurethane soft foam.

[0006] Preferably, in S1, the mass ratio of kaolin powder, dimethyl sulfoxide, and water is 1:7:2, the magnetic stirring temperature is 50-60℃, the magnetic stirring time is 12-36h, and methanol is added for washing during centrifugation.

[0007] Preferably, in S2, the mass ratio of DMSO-intercalated kaolin, potassium acetate, and water is 3:40:16, the magnetic stirring temperature is 20-25℃, the magnetic stirring speed is 400-600 r / min, the magnetic stirring time is 12-36 h, and anhydrous ethanol is added for washing during centrifugation.

[0008] Preferably, in S3, the mass ratio of potassium acetate intercalated kaolin, phenylphosphonic acid and water is 1:5:20, the magnetic stirring temperature is 20-25℃, the magnetic stirring time is 12-36h, the magnetic stirring speed is 400-600r / min, and anhydrous ethanol is added for washing during centrifugation.

[0009] Preferably, in S4, the mass ratio of phenylphosphonic acid intercalated kaolin, chitosan and water is 2:1:100, the magnetic stirring temperature is 20-25℃, and the magnetic stirring speed is 100-300 r / min.

[0010] Preferably, in step S4, after immersing in polyurethane foam, a vacuum is drawn, the immersion temperature is 20-25℃, the stirring speed is 80-200 r / min, and the stirring time is 4-6 h.

[0011] Preferably, in S5, the concentration of the glutaraldehyde ethanol solution is 0.5-2 mol / L, the stirring speed is 80-200 r / min, and the stirring time is 1-3 h.

[0012] Preferably, in S1-S5, the drying temperature is 50-100℃ and the drying time is 2-5 hours.

[0013] Flame-retardant polyurethane soft foam was prepared using the above-described method for preparing flame-retardant polyurethane soft foam based on phenylphosphonic acid intercalated kaolin.

[0014] The aforementioned flame-retardant polyurethane soft foam based on phenylphosphonic acid intercalated kaolin is used in the preparation of high-temperature thermal insulation and thermal protection materials for building insulation, transportation, and aerospace applications.

[0015] Therefore, the present invention employs the above-mentioned flame-retardant polyurethane soft foam based on phenylphosphonic acid intercalated kaolin, its preparation method, and its application, the beneficial effects of which are as follows: 1. This invention uses phenylphosphonic acid as a phosphorus source. It utilizes the hydrogen bond formed between the phenylphosphonic acid molecule and the hydroxyl group between the layers of kaolin. At the same time, the strong hydrophobic and large benzene ring at the other end of the phenylphosphonic acid molecule further expands and stabilizes the layered structure of kaolin. Thus, the phenylphosphonic acid molecule is inserted into the interlayer of potassium acetate intercalated kaolin, which promotes the formation of a dense carbonized layer or phosphate protective layer when exposed to heat, effectively inhibiting the release of combustible gases and reducing the smoke generation rate. 2. The chitosan-encapsulated phenylphosphonic acid intercalated kaolin coating prepared by this invention has a low heat release rate and smoke release rate, and at the same time has excellent flame retardant properties. Under heat exposure conditions, the chitosan-encapsulated phenylphosphonic acid intercalated kaolin coating can significantly reduce the release of combustible gases and the smoke generation rate. Therefore, both flame retardant polyurethane soft foam and chitosan-encapsulated phenylphosphonic acid intercalated kaolin coating are suitable for high-temperature insulation and thermal protection fields such as building insulation, transportation and aerospace. 3. The preparation method in this invention has the advantages of simple process and short preparation cycle; by controlling a specific mass ratio, phenylphosphonic acid is introduced as a phosphorus source to modify kaolin, so that the obtained flame-retardant polyurethane soft foam has the characteristics of excellent flame retardant performance and significant low smoke effect.

[0016] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0017] Figure 1 This is the XRD pattern of phenylphosphonic acid intercalated kaolin BK and kaolin in Example 2 of the present invention; Figure 2 This is a SEM image of phenylphosphonic acid intercalated kaolin BK in Example 2 of the present invention; Figure 3 This is the EDS diagram of phenylphosphonic acid intercalated kaolin BK in Example 2 of the present invention. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments. Unless otherwise defined, the technical or scientific terms used in this invention should be understood in their ordinary sense by those skilled in the art. The features mentioned above or in the specific examples mentioned in this invention can be combined arbitrarily, and these specific embodiments are only used to illustrate the invention and are not intended to limit the scope of the invention.

[0019] This invention provides a method for preparing flame-retardant polyurethane flexible foam based on phenylphosphonic acid intercalated kaolin, comprising the following steps: S1. Kaolin powder is added to dimethyl sulfoxide and water, and intercalation is performed under magnetic stirring. After centrifugation and drying, DMSO-intercalated kaolin is obtained. Kaolin is a layered silicate that provides the intercalation framework, enhancing physical barrier and thermal stability. DMSO can form hydrogen bonds with the interlayer hydroxyl groups of kaolin, opening up the interlayer spacing to achieve preliminary intercalation, resulting in DMSO-intercalated kaolin (DK), which lays the structural foundation for subsequent substitution.

[0020] S2. The DMSO-intercalated kaolin obtained in S1 is added to a potassium acetate aqueous solution and subjected to displacement intercalation treatment under magnetic stirring. After centrifugation and drying, potassium acetate-intercalated kaolin is obtained. The potassium ions of potassium acetate replace the DMSO between the kaolin layers, further expanding the interlayer spacing and introducing metal ions to enhance the interlayer stability, resulting in potassium acetate-intercalated kaolin (AK), which provides a more open interlayer environment for the insertion of phenylphosphonic acid.

[0021] S3. The potassium acetate-intercalated kaolin from S2 is added to an aqueous solution of phenylphosphonic acid, and a displacement intercalation treatment is performed under magnetic stirring. After centrifugation and drying, phenylphosphonic acid-intercalated kaolin is obtained. The phosphate groups in phenylphosphonic acid combine with potassium ions or hydroxyl groups between the kaolin layers to achieve displacement, introducing the flame-retardant element phosphorus and promoting the formation of a phosphate protective layer at high temperatures. The hydrophobicity and steric hindrance effect of the benzene ring further expand and stabilize the layered structure, enhancing the thermal stability and low smoke emission of the coating.

[0022] S4. Add the phenylphosphonic acid-intercalated kaolin obtained in S3 to the chitosan aqueous solution and mix under magnetic stirring to obtain a chitosan-coated phenylphosphonic acid-intercalated kaolin coating solution. After immersion in polyurethane foam, continue to stir slowly. After soaking, remove and dry to obtain intermediate polyurethane foam. Chitosan coats the phenylphosphonic acid-intercalated kaolin through hydrogen bonding and physical adsorption to form a uniform coating solution. The chitosan-coated phenylphosphonic acid-intercalated kaolin is fixed on the surface and pores of the polyurethane foam. Chitosan itself has certain flame retardant properties, which can synergistically enhance the effect.

[0023] S5. The intermediate polyurethane foam from S4 is immersed in a glutaraldehyde ethanol solution and stirred. After removal, it is dried to obtain flame-retardant polyurethane soft foam. Glutaraldehyde reacts with the amino groups in chitosan to form a Schiff base reaction, forming a three-dimensional network cross-linked structure, which enhances the mechanical strength and heat resistance of the coating and prevents the coating from peeling off in high-temperature or humid environments.

[0024] In some embodiments of the present invention, in S1, the mass ratio of kaolin powder, dimethyl sulfoxide, and water is 1:7:2; the magnetic stirring temperature is 50-60°C; the magnetic stirring time is 12-36 hours; and methanol is added for washing during centrifugation. Water is used for dispersion, and the dosage is set to ensure that DMSO is fully intercalated into kaolin. Methanol can effectively dissolve residual DMSO, and washing improves the purity of DMSO-intercalated kaolin.

[0025] In some embodiments of the present invention, in step S2, the mass ratio of DMSO-intercalated kaolin, potassium acetate, and water is 3:40:16; the magnetic stirring temperature is 20-25°C; the magnetic stirring speed is 400-600 r / min; and the magnetic stirring time is 12-36 h. Anhydrous ethanol is added for washing during centrifugation. The dosage is set to ensure that potassium acetate is in excess to drive the displacement reaction to completion. Anhydrous ethanol washing removes residual potassium acetate and byproducts.

[0026] In some embodiments of the present invention, in step S3, the mass ratio of potassium acetate intercalated kaolin, phenylphosphonic acid, and water is 1:5:20; the magnetic stirring temperature is 20-25°C; the magnetic stirring time is 12-36 hours; the magnetic stirring speed is 400-600 r / min; and anhydrous ethanol is added for washing during centrifugation. The dosage is set to ensure an excess of phenylphosphonic acid for complete displacement, and water provides the reaction medium. The temperature setting avoids the decomposition or volatilization of phenylphosphonic acid, and the anhydrous ethanol washing removes unreacted phenylphosphonic acid.

[0027] In some embodiments of the present invention, in S4, the mass ratio of phenylphosphonic acid intercalated kaolin, chitosan and water is 2:1:100, the temperature of magnetic stirring is 20-25°C, and the speed of magnetic stirring is 100-300 r / min.

[0028] In some embodiments of the present invention, in step S4, after immersion in polyurethane foam, a vacuum is applied. The immersion temperature is 20-25°C, the stirring speed is 80-200 r / min, and the stirring time is 4-6 h. Vacuuming removes air from the pores of the polyurethane foam, allowing the chitosan-coated phenylphosphonic acid intercalated kaolin liquid to fully penetrate.

[0029] In some embodiments of the present invention, in step S5, the concentration of the glutaraldehyde ethanol solution is 0.5-2 mol / L, the stirring speed is 80-200 r / min, and the stirring time is 1-3 h. Glutaraldehyde acts as a crosslinking agent to crosslink with chitosan amino groups, forming a three-dimensional network.

[0030] In some embodiments of the present invention, in S1-S5, the drying temperature is 50-100℃ and the drying time is 2-5h.

[0031] In some embodiments of the present invention, flame-retardant polyurethane soft foam is prepared using the above-described method for preparing flame-retardant polyurethane soft foam based on phenylphosphonic acid intercalated kaolin.

[0032] In some embodiments of the present invention, the flame-retardant polyurethane soft foam based on phenylphosphonic acid intercalated kaolin is applied to the preparation of high-temperature thermal insulation and thermal protection materials for building insulation, transportation and aerospace applications.

[0033] Example 1 S1. Kaolin powder was added to dimethyl sulfoxide and water in a mass ratio of 1:7:2. The mixture was magnetically stirred at 450 r / min for 24 h at 60 °C for intercalation treatment. After washing with methanol and centrifugation, the mixture was dried at 60 °C for 3 h to obtain DMSO-intercalated kaolin (DK).

[0034] S2. The DMSO-intercalated kaolin obtained in S1 was added to a potassium acetate aqueous solution at a mass ratio of 3:40:16. The mixture was magnetically stirred at 500 r / min for 24 h at 25 °C for displacement intercalation treatment. After washing with anhydrous ethanol and centrifugation, the mixture was dried at 60 °C for 3 h to obtain potassium acetate-intercalated kaolin (AK).

[0035] S3. The potassium acetate-intercalated kaolin from S2 was added to an aqueous solution of phenylphosphonic acid, with a mass ratio of potassium acetate-intercalated kaolin, phenylphosphonic acid, and water of 1:5:20. The mixture was magnetically stirred at 500 r / min for 24 h at 25 °C to perform displacement intercalation treatment. After washing with anhydrous ethanol, the mixture was centrifuged, dried, and then dried at 60 °C for 3 h to obtain phenylphosphonic acid-intercalated kaolin BK.

[0036] S4. Add the phenylphosphonic acid-intercalated kaolin obtained in S3 to a chitosan aqueous solution. The mass ratio of phenylphosphonic acid-intercalated kaolin, chitosan, and water is 2:1:100. Mix the mixture magnetically at 200 r / min and 25°C. After immersing the mixture in polyurethane foam at 25°C, apply a vacuum and stir slowly at 200 r / min for 5 hours. After immersion, remove the foam and dry it at 90°C for 2 hours to obtain the intermediate polyurethane foam.

[0037] S5. The intermediate polyurethane foam from S4 is immersed in a 1 mol / L glutaraldehyde ethanol solution and stirred for 2 hours at 100 r / min at 25°C. After removal, it is dried at 90°C for 2 hours to obtain flame-retardant polyurethane soft foam.

[0038] Example 2 S1. Kaolin powder was added to dimethyl sulfoxide and water in a mass ratio of 1:7:2. The mixture was magnetically stirred at 450 r / min for 24 h at 60 °C for intercalation treatment. After washing with methanol and centrifugation, the mixture was dried at 60 °C for 3 h to obtain DMSO-intercalated kaolin (DK).

[0039] S2. The DMSO-intercalated kaolin obtained in S1 was added to a potassium acetate aqueous solution at a mass ratio of 3:40:16. The mixture was magnetically stirred at 500 r / min for 24 h at 25 °C for displacement intercalation treatment. After washing with anhydrous ethanol and centrifugation, the mixture was dried at 60 °C for 3 h to obtain potassium acetate-intercalated kaolin (AK).

[0040] S3. The potassium acetate-intercalated kaolin from S2 was added to an aqueous solution of phenylphosphonic acid, with a mass ratio of potassium acetate-intercalated kaolin, phenylphosphonic acid, and water of 1:5:20. The mixture was magnetically stirred at 500 r / min for 24 h at 25 °C to perform displacement intercalation treatment. After washing with anhydrous ethanol, the mixture was centrifuged, dried, and then dried at 60 °C for 3 h to obtain phenylphosphonic acid-intercalated kaolin BK.

[0041] S4. Add the phenylphosphonic acid-intercalated kaolin obtained in S3 to a chitosan aqueous solution. The mass ratio of phenylphosphonic acid-intercalated kaolin, chitosan, and water is 5:1:100. Mix the mixture magnetically at 200 r / min and 25°C. After immersing the mixture in polyurethane foam at 25°C, apply a vacuum and stir slowly at 100 r / min for 5 hours. After immersion, remove the foam and dry it at 90°C for 2 hours to obtain the intermediate polyurethane foam.

[0042] S5. The intermediate polyurethane foam from S4 is immersed in a 1 mol / L glutaraldehyde ethanol solution and stirred for 2 hours at 100 r / min at 25°C. After removal, it is dried at 90°C for 2 hours to obtain flame-retardant polyurethane soft foam.

[0043] Example 3 S1. Kaolin powder was added to dimethyl sulfoxide and water in a mass ratio of 1:7:2. The mixture was magnetically stirred at 450 r / min for 24 h at 60 °C for intercalation treatment. After washing with methanol and centrifugation, the mixture was dried at 60 °C for 3 h to obtain DMSO-intercalated kaolin (DK).

[0044] S2. The DMSO-intercalated kaolin obtained in S1 was added to a potassium acetate aqueous solution at a mass ratio of 3:40:16. The mixture was magnetically stirred at 500 r / min for 24 h at 25 °C for displacement intercalation treatment. After washing with anhydrous ethanol and centrifugation, the mixture was dried at 60 °C for 3 h to obtain potassium acetate-intercalated kaolin (AK).

[0045] S3. The potassium acetate-intercalated kaolin from S2 was added to an aqueous solution of phenylphosphonic acid, with a mass ratio of potassium acetate-intercalated kaolin, phenylphosphonic acid, and water of 1:5:20. The mixture was magnetically stirred at 500 r / min for 24 h at 25 °C to perform displacement intercalation treatment. After washing with anhydrous ethanol, the mixture was centrifuged, dried, and then dried at 60 °C for 3 h to obtain phenylphosphonic acid-intercalated kaolin BK.

[0046] S4. Add the phenylphosphonic acid-intercalated kaolin obtained in S3 to a chitosan aqueous solution. The mass ratio of phenylphosphonic acid-intercalated kaolin, chitosan, and water is 8:1:100. Mix the mixture magnetically at 200 r / min and 25°C. After immersing the mixture in polyurethane foam at 25°C, apply a vacuum and stir slowly at 100 r / min for 5 hours. After immersion, remove the foam and dry it at 90°C for 2 hours to obtain the intermediate polyurethane foam.

[0047] S5. The intermediate polyurethane foam from S4 is immersed in a 1 mol / L glutaraldehyde ethanol solution and stirred for 2 hours at 100 r / min at 25°C. After removal, it is dried at 90°C for 2 hours to obtain flame-retardant polyurethane soft foam.

[0048] Comparative Example 1 S1, kaolin, chitosan, and water were mixed in a mass ratio of 5:1:100. Kaolin was added to the chitosan aqueous solution and magnetically stirred at 200 rpm at 25°C. The mixture was then immersed in polyurethane foam at 25°C, followed by vacuuming and slow stirring at 100 rpm for 5 hours. After immersion, the foam was removed, dried, and then dried at 90°C for 2 hours to obtain the intermediate polyurethane foam.

[0049] S2. The intermediate polyurethane foam from S1 is immersed in a 1 mol / L glutaraldehyde ethanol solution and stirred for 2 hours at 100 r / min at 25°C. After removal, it is dried at 90°C for 2 hours to obtain polyurethane soft foam.

[0050] Comparative Example 2 S1. A chitosan aqueous solution was prepared by mixing chitosan and water at a mass ratio of 1:100 and magnetically stirring at 200 r / min at 25°C. The mixture was then immersed in polyurethane foam at 25°C and vacuumed while being slowly stirred at 100 r / min for 5 hours. After immersion, the foam was removed, dried, and then dried at 90°C for 2 hours to obtain the intermediate polyurethane foam.

[0051] S2. The intermediate polyurethane foam from S1 is immersed in a 1 mol / L glutaraldehyde ethanol solution and stirred for 2 hours at 100 r / min at 25°C. After removal, it is dried at 90°C for 2 hours to obtain polyurethane soft foam.

[0052] Performance testing The specific surface area, pore volume, and average pore size of kaolin, DMSO-intercalated kaolin (DK), potassium acetate-intercalated kaolin (AK), and phenylphosphonic acid-intercalated kaolin (BK) in Example 1 were measured, and the results are shown in Table 1. It can be seen that with the progress of the preparation steps, the specific surface area, pore volume, and average pore size of kaolin all show a decreasing trend. This indicates that phenylphosphonic acid intercalation can effectively disrupt the interlayer hydrogen bonds in kaolin, expand the interlayer spacing, significantly improve its pore volume and average pore size, and shift the pore size distribution from micropore-dominated to mesopore-dominated, thereby greatly improving its porous structure properties.

[0053] Table 1. Specific surface area, pore volume, and average pore size data.

[0054] The flame-retardant polyurethane soft foams prepared in Examples 1-3 and the polyurethane soft foams in Comparative Examples 1-2 were subjected to XRD, SEM, and limiting oxygen index tests, as follows: Figures 1-3 As shown, it can be seen that the XRD of the phenylphosphonic acid modified phosphorus intercalated kaolin in Examples 1-3 is shifted from the (001) diffraction peak of the unmodified kaolin in Comparative Example 1, and a new diffraction peak appears at 2θ=5.95Å. At the same time, EDS energy dispersive spectroscopy analysis shows that phosphorus is uniformly distributed in kaolin, indicating that phenylphosphonic acid was successfully inserted into the interlayer of kaolin.

[0055] The thermal conductivity of the flame-retardant polyurethane soft foams prepared in Examples 1-3 and the polyurethane soft foams in Comparative Examples 1-2 are shown in Table 2.

[0056] Table 2 Thermal conductivity of Examples 1-3 and Comparative Examples 1-2

[0057] As shown in Table 2, the thermal conductivity of the flame-retardant polyurethane soft foam prepared in Examples 1-3 of the present invention is between 0.0432 W / (m·K) and 0.1169 W / (m·K), indicating that the polyurethane soft foam prepared by the method in Examples 1-3 has high thermal insulation performance.

[0058] The flame-retardant polyurethane soft foam prepared in Example 2 and the polyurethane soft foam in Comparative Examples 1-2 were tested for combustion performance, and the results are shown in Table 3.

[0059] Table 3 Combustion performance data of Example 2 and Comparative Examples 1-2

[0060] As shown in Table 3, compared to Comparative Examples 1 and 2, Example 2 exhibits significantly superior overall fire safety characteristics in the combustion performance test, fully demonstrating that its formulation design or material structure optimization has an efficient flame-retardant mechanism. Firstly, its measured limiting oxygen index (LOI) is as high as 32.5%, far exceeding the standard value (26%) for general flame-retardant materials, indicating that this material is extremely difficult to ignite at room temperature and possesses excellent self-extinguishing ability. More importantly, the maximum heat release rate (pHRR) of Example 2 is as low as 107.3 kW·m³. -2 This significantly suppressed flame propagation speed and the risk of flashover. Furthermore, the total smoke emission (TSP) in Example 2 was only 0.36 m³. 2 This is far lower than the 1.97m of Comparative Example 2. 2 This indicates that it produces very little smoke when burning, which helps ensure the visibility of escape routes and reduces the risk of suffocation and poisoning.

[0061] Therefore, the present invention employs the above-mentioned flame-retardant polyurethane soft foam based on phenylphosphonic acid intercalated kaolin, its preparation method and application. The prepared chitosan-encapsulated phenylphosphonic acid intercalated kaolin coating has a low heat release rate and smoke release rate, and at the same time has excellent flame-retardant properties. The chitosan-encapsulated phenylphosphonic acid intercalated kaolin coating and the flame-retardant polyurethane soft foam can significantly reduce the release of combustible gases and the smoke generation rate under heat exposure conditions.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing flame-retardant polyurethane flexible foam based on phenylphosphonic acid intercalated kaolin, characterized in that: Includes the following steps: S1. Add kaolin powder to dimethyl sulfoxide and water, perform intercalation treatment under magnetic stirring, and obtain DMSO intercalated kaolin after centrifugation and drying. S2. Add the DMSO-intercalated kaolin obtained in S1 to a potassium acetate aqueous solution, perform displacement intercalation treatment under magnetic stirring, and obtain potassium acetate-intercalated kaolin after centrifugation and drying. S3. Add the potassium acetate intercalated kaolin from S2 to a phenylphosphonic acid aqueous solution, perform displacement intercalation treatment under magnetic stirring, and obtain phenylphosphonic acid intercalated kaolin after centrifugation and drying. S4. Add the phenylphosphonic acid intercalated kaolin obtained in S3 to the chitosan aqueous solution, mix under magnetic stirring, immerse in polyurethane foam and continue to stir slowly, remove and dry after soaking to obtain intermediate polyurethane foam. S5. Immerse the intermediate polyurethane foam from S4 in a glutaraldehyde ethanol solution and stir. Remove and dry to obtain flame-retardant polyurethane soft foam.

2. The method for preparing flame-retardant polyurethane flexible foam based on phenylphosphonic acid intercalated kaolin according to claim 1, characterized in that: In S1, the mass ratio of kaolin powder, dimethyl sulfoxide, and water is 1:7:

2. The magnetic stirring temperature is 50-60℃, and the magnetic stirring time is 12-36h. Methanol is added for washing during centrifugation.

3. The method for preparing flame-retardant polyurethane flexible foam based on phenylphosphonic acid intercalated kaolin according to claim 1, characterized in that: In S2, the mass ratio of DMSO-intercalated kaolin, potassium acetate, and water is 3:40:

16. The magnetic stirring temperature is 20-25℃, the magnetic stirring speed is 400-600 r / min, and the magnetic stirring time is 12-36 h. Anhydrous ethanol is added for washing during centrifugation.

4. The method for preparing flame-retardant polyurethane flexible foam based on phenylphosphonic acid intercalated kaolin according to claim 1, characterized in that: In S3, the mass ratio of potassium acetate intercalated kaolin, phenylphosphonic acid and water is 1:5:

20. The magnetic stirring temperature is 20-25℃, the magnetic stirring time is 12-36h, the magnetic stirring speed is 400-600r / min, and anhydrous ethanol is added for washing during centrifugation.

5. The method for preparing flame-retardant polyurethane flexible foam based on phenylphosphonic acid intercalated kaolin according to claim 1, characterized in that: In S4, the mass ratio of phenylphosphonic acid intercalated kaolin, chitosan, and water is 2:1:100, the magnetic stirring temperature is 20-25℃, and the magnetic stirring speed is 100-300 r / min.

6. The method for preparing flame-retardant polyurethane flexible foam based on phenylphosphonic acid intercalated kaolin according to claim 1, characterized in that: In S4, after immersing in polyurethane foam, vacuum is applied. The immersion temperature is 20-25℃, the stirring speed is 80-200 r / min, and the stirring time is 4-6 h.

7. The method for preparing flame-retardant polyurethane flexible foam based on phenylphosphonic acid intercalated kaolin according to claim 1, characterized in that: In S5, the concentration of glutaraldehyde ethanol solution is 0.5-2 mol / L, the stirring speed is 80-200 r / min, and the stirring time is 1-3 h.

8. The method for preparing flame-retardant polyurethane flexible foam based on phenylphosphonic acid intercalated kaolin according to claim 1, characterized in that: In S1-S5, the drying temperature is 50-100℃, and the drying time is 2-5 hours.

9. A flame-retardant polyurethane flexible foam based on phenylphosphonic acid intercalated kaolin, characterized in that: It was prepared using the method for preparing flame-retardant polyurethane soft foam based on phenylphosphonic acid intercalated kaolin as described in any one of claims 1-8.

10. An application of a flame-retardant polyurethane flexible foam based on phenylphosphonic acid intercalated kaolin, characterized in that: The flame-retardant polyurethane soft foam based on phenylphosphonic acid intercalated kaolin as described in claim 9 is used in the preparation of high-temperature thermal insulation and thermal protection materials for building insulation, transportation and aerospace applications.

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