Preparation method of green bio-based composite flame retardant coating and application of green bio-based composite flame retardant coating in polyurethane foam
By modifying the multi-component flame retardant coating formed by chitosan, gelatin, ammonium polyphosphate and sodium montmorillonite, the problem of flammability of polyurethane foam is solved, and an efficient and environmentally friendly flame retardant effect is achieved, and the coating process is simplified.
Patent Information
- Application Number
- CN202510806611.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-17
- Publication Date
- 2025-08-15
AI Technical Summary
Existing polyurethane foam is flammable, and it releases heat and toxic gases during combustion. The existing flame retardants have problems such as difficulty in dispersion, migration, high cost, and great impact on substrate performance.
Modified chitosan, gelatin, ammonium polyphosphate and sodium montmorillonite are used to form a multi-component flame retardant coating, and a stable sol gel liquid is formed in water and ethanol solvents through cross-linking and hydrogen bonding, achieving uniform coating of polyurethane foam.
It significantly improves the flame retardant performance of polyurethane foam, controls the heat release rate, smoke release rate and total heat release amount, enhances the density of the carbon layer, simplifies the coating process, and is environmentally friendly.
Smart Images
Figure CN120484576A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of flame-retardant polymer materials, and in particular to a method for preparing a green bio-based composite flame retardant coating and application of the coating in polyurethane foam. Background Art
[0002] Polyurethane foam (PUF) is widely used in electronics, transportation, building materials, and household products, and has become an indispensable part of modern life. However, PU foam is flammable, releasing large amounts of heat, toxic gases, and smoke. This poses a significant threat to human life and property, and can also lead to serious problems such as environmental pollution. Therefore, flame-retardant treatment of PU foam is crucial to reducing its fire safety risks.
[0003] Additive flame retardants come in both liquid and solid forms. Solid flame retardants are difficult to disperse, and when added in large quantities, the system viscosity increases, making processing difficult and leading to a decrease in the mechanical properties of the substrate material. Liquid flame retardants are also less stable and can migrate during use, causing flame retardancy to decrease over time. Reactive flame retardants effectively address the issues of migration and precipitation of additive flame retardants while having minimal impact on the performance of the substrate itself. However, these reactive flame retardants require a high degree of reactivity in the foaming substrate and still suffer from complex molecular design, cumbersome preparation processes, and high application costs. Summary of the Invention
[0004] To address the shortcomings of the aforementioned technologies, this application provides a green, bio-based composite flame-retardant coating. This coating utilizes the cross-linking and intermolecular hydrogen bonding between the abundant amino groups in modified chitosan, the abundant amino groups in gelatin, and the phosphate groups and ammonium ions in ammonium polyphosphate, along with physically exfoliated sodium montmorillonite, to form a uniform and stable sol-gel solution (DCS / DEL / APP / MMT) in water and ethanol solvents. This multi-component flame retardant enhances the flame retardancy of polyurethane foam through synergistic action, addressing existing flame-retardant coating issues such as uneven distribution of the multi-phase flame retardant system, poor adhesion between the coating and the substrate, and the need for repeated deposition of the coating.
[0005] To achieve the above objectives, the present application provides a method for preparing a green bio-based composite flame retardant coating, comprising the following steps: S1. Dissolve p-hydroxybenzaldehyde in tetrahydrofuran, then add triethylamine, transfer the mixture into a reactor, and then dropwise add diphenyldichlorosilane into the reactor, stir, filter, and rotary evaporate to obtain 4,4'-(diphenylsilanediyl)bis(oxy)dibenzaldehyde; the reaction formula is as follows:
[0006] S2. Add chitosan to methanol and stir, then add 4,4'-(diphenylsilanediyl)bis(oxy)benzaldehyde, heat and stir, then cool, filter, wash and dry to obtain modified chitosan; the chemical formula is:
[0007] S3, adding the modified chitosan to deionized water, adjusting the pH, stirring, heating, and then adding gelatin and stirring to obtain a modified chitosan / gelatin mixed solution; S4, adding ammonium polyphosphate to anhydrous ethanol, ultrasonicating, stirring, and then adding to the modified chitosan / gelatin mixture, heating and stirring to obtain a mixture A; S5. Dispersing sodium montmorillonite in deionized water, ultrasonicating and stirring to obtain dispersion B; S6. Add the dispersion B to the mixed solution A, heat, stir, and allow to stand to obtain a green bio-based composite flame retardant coating.
[0008] In the above process, chitosan is one of the most commonly used carbon-forming agents in intumescent flame retardants, and has the characteristics of biodegradability, high thermal stability and antibacterial properties; ammonium polyphosphate absorbs a large amount of heat when thermally decomposed, reducing the temperature of the substrate, and at the same time releases non-combustible gases to dilute the oxygen concentration and delay the combustion process; gelatin exhibits rich reactive groups and high nitrogen content, and can be used as a carbonizing agent; sodium montmorillonite, as a natural inorganic material, has a unique two-dimensional layered structure that can effectively suppress the smoke produced during combustion.
[0009] Furthermore, the molar ratio of the added amounts of p-hydroxybenzaldehyde and triethylamine in step S1 is 1:1-2.
[0010] Furthermore, the temperature of the rotary evaporation is 45-55°C.
[0011] Furthermore, in step S2, the molar ratio of the chitosan to 4,4'-(diphenylsilanediyl)bis(oxy)benzaldehyde is 1:1-2.
[0012] Furthermore, the pH is adjusted to 5-6.
[0013] Furthermore, the temperature is raised to 40-80° C. in step S3.
[0014] Furthermore, the total mass of the modified chitosan and ammonium polyphosphate accounts for 7-9% of the green bio-based composite flame retardant coating in terms of mass ratio, wherein the mass ratio of the modified chitosan and ammonium polyphosphate is 1:1 or 1:2 or 1:3 or 1:4.
[0015] The present application also provides a method for preparing a green bio-based composite flame retardant coating and its application in polyurethane foam.
[0016] The present application also provides a method for preparing a green bio-based composite flame retardant coating and the use of the green bio-based composite flame retardant coating in polyurethane foam.
[0017] In summary, this application has the following beneficial effects: The present application provides a method for preparing a green bio-based composite flame retardant coating. Ammonium polyphosphate serves as an acid source and a gas source, and decomposes at high temperature to generate polyphosphoric acid and ammonia. Polyphosphoric acid serves as a strong dehydrating agent to promote the dehydration and carbonization of a carbonizing agent to form an expanded carbon layer. Ammonia dilutes the oxygen concentration and inhibits the combustion chain reaction, thus serving as a gas-phase flame retardant. The amino and hydroxyl groups of modified chitosan form an expanded carbon layer during combustion, which blocks the transfer of heat and oxygen. The amino groups can react with APP decomposition products (such as polyphosphoric acid) to form a cross-linked network, thereby enhancing the density of the carbon layer and serving as a solid-phase flame retardant. The gas phase and solid phase work synergistically to enhance the flame retardant effect.
[0018] Through physical and chemical effects such as cross-linking reactions and intermolecular hydrogen bonds, a stable multi-component sol-gel liquid was successfully constructed. The sol-gel liquid has green, environmentally friendly and non-toxic characteristics, and can achieve uniform coating of polyurethane foam by direct brushing or dipping process, which significantly simplifies the tedious process of traditional step-by-step coating. By regulating the ratio of each flame retardant component, the flame retardant properties of the sol-gel liquid can be accurately adjusted. The polyurethane foam treated with the sol-gel liquid shows significantly improved flame retardant properties during the combustion process, including key parameters such as heat release rate, smoke release rate, total heat release and total smoke release. All are effectively controlled, and the amount of residual carbon is significantly increased. The green bio-based composite flame retardant coating provided in this application has a simple preparation process and is environmentally friendly, and has broad application prospects in the field of flame retardant polymer materials. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0020] Figure 1 This is a stability diagram of the DCS / DEL / 3APP / MMT green bio-based composite flame retardant coating prepared in Example 3 of the present invention when stored at room temperature; Figure 2 Thermogravimetric curves of the blank polyurethane foam of the present invention, the dried sample of the green bio-based composite flame retardant coating prepared in Example 3, and the flame retardant foam thereof; Figure 3 (a) Heat release rate diagram of DCS / DEL / 3APP / MMT to FPUF prepared in Example 3 of the present invention; Figure 3 (b) is a graph showing the total heat release of FPUF by DCS / DEL / 3APP / MMT prepared in Example 3 of the present invention; Figure 3 (c) is a graph showing the smoke release rate of DCS / DEL / 3APP / MMT to FPUF prepared in Example 3 of the present invention; Figure 3 (d) is a graph showing the total smoke release of FPUF by DCS / DEL / 3APP / MMT prepared in Example 3 of the present invention. DETAILED DESCRIPTION
[0021] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.
[0022] The raw materials involved in the specific implementation of this application are of analytical grade.
[0023] Example 1 A method for preparing a green bio-based composite flame retardant coating comprises the following steps: S1. Dissolve p-hydroxybenzaldehyde in tetrahydrofuran at a volume ratio of 1:10, and add triethylamine to the solution in a molar ratio of 1:1 with p-hydroxybenzaldehyde. Transfer the mixture to a four-necked flask equipped with a nitrogen inlet and a condenser. Then, add diphenyldichlorosilane dropwise to the four-necked flask in an ice-water bath and add it in a molar ratio of 1:1 with p-hydroxybenzaldehyde. Then, stir the reaction at 40°C for 4 hours, filter, and then rotary evaporate (50°C) until no droplets flow to obtain the organic intermediate 4,4'-(diphenylsilanediyl)bis(oxy))dibenzaldehyde (DPP). S2. Chitosan was added to a three-necked flask containing methanol at a concentration of 3% (w / v). The mixture was stirred, condensed, and refluxed for 1.5 h to fully swell the chitosan. DPP was slowly added to the three-necked flask in a molar ratio of 1:1 with chitosan. The mixture was heated to 70°C and stirred for 12 h. The mixture was then cooled and filtered. The mixture was then rinsed with acetone and ethanol three times, respectively, and dried in a vacuum drying oven at 60°C for 5 h to obtain modified chitosan. S3. Add 4 g of modified chitosan to 80 mL of deionized water, adjust the pH to 5, stir until completely dissolved, then heat to 60°C, then slowly add 1.5 g of gelatin, continue stirring until dissolved, and obtain a modified chitosan / gelatin mixture; S4. Add 4 g of ammonium polyphosphate to 10 mL of anhydrous ethanol, then ultrasonicate (30 kHz, 250 W) for 1 h and stir for 5 h. Then slowly add the mixture to the modified chitosan / gelatin solution, heat to 40 °C, and stir to obtain a mixture A. S5. Disperse 2 g of sodium montmorillonite in 10 mL of deionized water, ultrasonicate (30 kHz, 250 W) and stir until fully exfoliated to obtain dispersion B. S6. Add dispersion B to mixed solution A, heat to 40°C, stir evenly, and then let stand for 3 hours to obtain a green bio-based composite flame retardant coating (DCS / DEL / APP / MMT).
[0024] Example 2 A method for preparing a green bio-based composite flame retardant coating comprises the following steps: S1. Dissolve p-hydroxybenzaldehyde in tetrahydrofuran at a volume ratio of 1:10, and add triethylamine to the solution in a molar ratio of 1:1 with p-hydroxybenzaldehyde. Transfer the mixture to a four-necked flask equipped with a nitrogen inlet and a condenser. Then, add diphenyldichlorosilane dropwise to the four-necked flask in an ice-water bath and add it in a molar ratio of 1:1 with p-hydroxybenzaldehyde. Then, stir the reaction at 40°C for 4 hours, filter, and then rotary evaporate (50°C) until no droplets flow to obtain the organic intermediate 4,4'-(diphenylsilanediyl)bis(oxy))dibenzaldehyde (DPP). S2. Chitosan was added to a three-necked flask containing methanol at a concentration of 3% (w / v). The mixture was stirred, condensed, and refluxed for 1.5 h to fully swell the chitosan. DPP was slowly added to the three-necked flask in a molar ratio of 1:1 with chitosan. The mixture was heated to 70°C and stirred for 12 h. The mixture was then cooled and filtered. The mixture was then rinsed with acetone and ethanol three times, respectively, and dried in a vacuum drying oven at 60°C for 5 h to obtain modified chitosan. S3. Add 2.67 g of modified chitosan to 80 mL of deionized water, adjust the pH to 5, stir until completely dissolved, then heat to 60°C, then slowly add 1.5 g of gelatin, continue stirring until dissolved, and obtain a modified chitosan / gelatin mixture; S4. Add 5.33 g of ammonium polyphosphate to 10 mL of anhydrous ethanol, then sonicate (30 kHz, 250 W) for 1 h and stir for 5 h. Then slowly add the mixture to the modified chitosan / gelatin solution, heat to 40 °C, and stir to obtain a mixture A. S5. Disperse 2 g of sodium montmorillonite in 10 mL of deionized water, ultrasonicate (30 kHz, 250 W) and stir until fully exfoliated to obtain dispersion B. S6. Add dispersion B to mixed solution A, heat to 40°C, stir evenly, and then let stand for 3 hours to obtain a green bio-based composite flame retardant coating (DCS / DEL / 2APP / MMT).
[0025] Example 3 A method for preparing a green bio-based composite flame retardant coating comprises the following steps: S1. Dissolve p-hydroxybenzaldehyde in tetrahydrofuran at a volume ratio of 1:10, and add triethylamine to the solution in a molar ratio of 1:1 with p-hydroxybenzaldehyde. Transfer the mixture to a four-necked flask equipped with a nitrogen inlet and a condenser. Then, add diphenyldichlorosilane dropwise to the four-necked flask in an ice-water bath and add it in a molar ratio of 1:1 with p-hydroxybenzaldehyde. Then, stir the reaction at 40°C for 4 hours, filter, and then rotary evaporate (50°C) until no droplets flow to obtain the organic intermediate 4,4'-(diphenylsilanediyl)bis(oxy))dibenzaldehyde (DPP). S2. Chitosan was added to a three-necked flask containing methanol at a concentration of 3% (w / v). The mixture was stirred, condensed, and refluxed for 1.5 h to fully swell the chitosan. DPP was slowly added to the three-necked flask in a molar ratio of 1:1 with chitosan. The mixture was heated to 70°C and stirred for 12 h. The mixture was then cooled and filtered. The mixture was then rinsed with acetone and ethanol three times, respectively, and dried in a vacuum drying oven at 60°C for 5 h to obtain modified chitosan. S3. Add 2 g of modified chitosan to 80 mL of deionized water, adjust the pH to 5, stir until completely dissolved, then heat to 60°C, then slowly add 1.5 g of gelatin, continue stirring until dissolved, and obtain a modified chitosan / gelatin mixture; S4. Add 6 g of ammonium polyphosphate to 10 mL of anhydrous ethanol, then sonicate (30 kHz, 250 W) for 1 h and stir for 5 h. Then slowly add the mixture to the modified chitosan / gelatin solution, heat to 40 °C, and stir to obtain a mixture A. S5. Disperse 2 g of sodium montmorillonite in 10 mL of deionized water, ultrasonicate (30 kHz, 250 W) and stir until fully exfoliated to obtain dispersion B. S6. Add dispersion B to mixed solution A, heat to 40°C, stir evenly, and then let stand for 3 hours to obtain a green bio-based composite flame retardant coating (DCS / DEL / 3APP / MMT).
[0026] Example 4 A method for preparing a green bio-based composite flame retardant coating comprises the following steps: S1. Dissolve p-hydroxybenzaldehyde in tetrahydrofuran at a volume ratio of 1:10, and add triethylamine to the solution in a molar ratio of 1:1 with p-hydroxybenzaldehyde. Transfer the mixture to a four-necked flask equipped with a nitrogen inlet and a condenser. Then, add diphenyldichlorosilane dropwise to the four-necked flask in an ice-water bath and add it in a molar ratio of 1:1 with p-hydroxybenzaldehyde. Then, stir the reaction at 40°C for 4 hours, filter, and then rotary evaporate (50°C) until no droplets flow to obtain the organic intermediate 4,4'-(diphenylsilanediyl)bis(oxy))dibenzaldehyde (DPP). S2. Chitosan was added to a three-necked flask containing methanol at a concentration of 3% (w / v). The mixture was stirred, condensed, and refluxed for 1.5 h to fully swell the chitosan. DPP was slowly added to the three-necked flask in a molar ratio of 1:1 with chitosan. The mixture was heated to 70°C and stirred for 12 h. The mixture was then cooled and filtered. The mixture was then rinsed with acetone and ethanol three times, respectively, and dried in a vacuum drying oven at 60°C for 5 h to obtain modified chitosan. S3. Add 1.6 g of modified chitosan to 80 mL of deionized water, adjust the pH to 5, stir until completely dissolved, then heat to 60°C, then slowly add 1.5 g of gelatin, continue stirring until dissolved, and obtain a modified chitosan / gelatin mixture; S4. Add 6.4 g of ammonium polyphosphate to 10 mL of anhydrous ethanol, then ultrasonicate (30 kHz, 250 W) for 1 h and stir for 5 h. Then slowly add the mixture to the modified chitosan / gelatin solution, heat to 40 °C, and stir to obtain a mixture A. S5. Disperse 2 g of sodium montmorillonite in 10 mL of deionized water, ultrasonicate (30 kHz, 250 W) and stir until fully exfoliated to obtain dispersion B. S6. Add dispersion B to mixed solution A, heat to 40°C, stir evenly, and then let stand for 3 hours to obtain a green bio-based composite flame retardant coating (DCS / DEL / 4APP / MMT).
[0027] Comparative Example 1 The difference between this comparative example and Example 3 is that the preparation method of a green bio-based composite flame retardant coating of the present application specifically includes the following steps: S1. Dissolve p-hydroxybenzaldehyde in tetrahydrofuran at a volume ratio of 1:10, and add triethylamine to the solution in a molar ratio of 1:1 with p-hydroxybenzaldehyde. Transfer the mixture to a four-necked flask equipped with a nitrogen inlet and a condenser. Then, add diphenyldichlorosilane dropwise to the four-necked flask in an ice-water bath and add it in a molar ratio of 1:1 with p-hydroxybenzaldehyde. Then, stir the reaction at 40°C for 4 hours, filter, and then rotary evaporate (50°C) until no droplets flow to obtain the organic intermediate 4,4'-(diphenylsilanediyl)bis(oxy))dibenzaldehyde (DPP). S2. Chitosan was added to a three-necked flask containing methanol at a concentration of 3% (w / v). The mixture was stirred, condensed, and refluxed for 1.5 h to fully swell the chitosan. DPP was slowly added to the three-necked flask in a molar ratio of 1:1 with chitosan. The mixture was heated to 70°C and stirred for 12 h. The mixture was then cooled and filtered. The mixture was then rinsed with acetone and ethanol three times, respectively, and dried in a vacuum drying oven at 60°C for 5 h to obtain modified chitosan. S3. Add 2 g of modified chitosan to 80 mL of deionized water, adjust the pH to 5-6, stir until completely dissolved, then raise the temperature to 40-80°C, then slowly add 1.5 g of gelatin, continue stirring until dissolved, and obtain a modified chitosan / gelatin mixture; S4, 6 g of ammonium polyphosphate was added to 10 mL of anhydrous ethanol, and then ultrasonicated (30 kHz, 250 W) for 1 hour and stirred for 5 hours, and then slowly added to the modified chitosan / gelatin mixture to obtain a mixture A; S5. Disperse 2 g of carbon black in 10 mL of deionized water, ultrasonicate (30 kHz, 250 W) and stir to obtain dispersion B. S6. Add the dispersion B to the mixed solution A, heat it to 40°C, stir it evenly, and then let it stand for 3 hours to obtain a green bio-based composite flame retardant coating.
[0028] Comparative Example 2 The difference between this comparative example and Example 3 is that the method for preparing a green bio-based composite flame retardant coating of the present application specifically includes the following steps: S1. Dissolve p-hydroxybenzaldehyde in tetrahydrofuran at a volume ratio of 1:10, and add triethylamine to the solution in a molar ratio of 1:1 with p-hydroxybenzaldehyde. Transfer the mixture to a four-necked flask equipped with a nitrogen inlet and a condenser. Then, add diphenyldichlorosilane dropwise to the four-necked flask in an ice-water bath and add it in a molar ratio of 1:1 with p-hydroxybenzaldehyde. Then, stir the reaction at 40°C for 4 hours, filter, and then rotary evaporate (50°C) until no droplets flow to obtain the organic intermediate 4,4'-(diphenylsilanediyl)bis(oxy))dibenzaldehyde (DPP). S2. Chitosan was added to a three-necked flask containing methanol at a concentration of 3% (w / v). The mixture was stirred, condensed, and refluxed for 1.5 h to fully swell the chitosan. DPP was slowly added to the three-necked flask in a molar ratio of 1:1 with chitosan. The mixture was heated to 70°C and stirred for 12 h. The mixture was then cooled and filtered. The mixture was then rinsed with acetone and ethanol three times, respectively, and dried in a vacuum drying oven at 60°C for 5 h to obtain modified chitosan. S3. Add 8 g of modified chitosan to 80 mL of deionized water, adjust the pH to 5, stir until completely dissolved, then heat to 60°C, then slowly add 1.5 g of gelatin, continue stirring until dissolved, and obtain a modified chitosan / gelatin mixture; S4. Disperse 2 g of sodium montmorillonite in 10 mL of deionized water, sonicate (30 kHz, 250 W) and stir until fully exfoliated to obtain dispersion B. S4. Disperse 2 g of sodium montmorillonite in 10 mL of deionized water, sonicate (30 kHz, 250 W) and stir until fully exfoliated to obtain dispersion A. S5. Add dispersion A to the modified chitosan / gelatin mixture, heat to 40° C., stir evenly, and then let stand for 3 hours to obtain a green bio-based composite flame retardant coating.
[0029] Performance Testing Functionality tests were performed on the green bio-based composite flame retardant coatings prepared in Examples 1-4 and Control Examples 1-2. The prepared green bio-based composite flame retardant coatings were brush-coated on the FPUF surface at a rate of 1 g per square centimeter.
[0030] The flame retardant properties of the green bio-based composite flame retardant coatings prepared in Examples 1-4 and Comparative Examples 1-2 were tested for limiting oxygen index and vertical combustion. The results are shown in Table 1 below: Table 1
[0031] In Table 1 above, LOI is the limiting oxygen index value; UL-94 represents the vertical burning rating Analysis of the data in Table 1 shows that the green bio-based composite flame retardant coatings prepared in Examples 1-4 have a limiting oxygen index greater than 30, and the vertical combustion ratings all reach V0. By comparing Examples 1-4, the ratio of modified chitosan to ammonium polyphosphate of 1:3 has the best flame retardant effect. While the limiting oxygen index of Control Examples 1 and 2, which lack flame retardant ingredients, is less than 30, the vertical rating is V1. Therefore, it can be seen that the green bio-based composite flame retardant coatings prepared in Examples 1-4 of the present application have good flame retardant effects, especially Example 3 has the best effect.
[0032] Figure 1 This is a stability diagram of the DCS / DEL / 3APP / MMT green bio-based composite flame retardant coating prepared in Example 3 when stored at room temperature. It can be seen from the figure that the flame retardant sol-gel solution is still in a stable state after long-term storage for thirty days.
[0033] Figure 2The thermogravimetric curves of the blank polyurethane foam (FPUF) of the present invention, the dried sample of the green bio-based composite flame retardant coating prepared in Example 3 (DCS / DEL / 3APP / MMT), and the flame retardant foam (FPUF / DCS / DEL / 3APP / MMT) thereof are shown in Table 2 below. Table 2
[0034] From Table 2 we can see that T 5% T is the temperature at which the sample mass loss reaches 5%; max1 and T max2 are the maximum decomposition temperatures of the sample in the first and second stages, respectively; the residual carbon content is the mass percentage of residual carbon in the sample at 800°C.
[0035] From the above data analysis, it can be seen that at 800°C, the residual carbon rate of pure polyurethane foam is 9.3%, the residual carbon rate of DCS / DEL / 3APP / MMT powder after drying is 56.7%, and the residual carbon rate of the sample coated with flame retardant coating FPUF / DCS / DEL / 3APP / MMT is 60.7%. It can be seen that the green bio-based composite flame retardant coating prepared in Example 3 of this application has a good flame retardant effect.
[0036] In order to determine the bonding strength between the green bio-based composite flame retardant coating prepared in Example 3 and Comparative Examples 1-2 and the substrate, a thermal shock test was performed. The prepared green bio-based composite flame retardant coating was brush-coated on the FPUF surface at a rate of 1 g per square centimeter. The sample was placed in a 140°C oven for 5 minutes, then taken out and placed in a refrigerator at approximately -20°C for 5 minutes. The above steps were repeated 5 times, and then the flame retardant performance was tested using a limiting oxygen index vertical combustion method. The results are shown in Table 3 below. Table 3
[0037] In Table 3 above, LOI is the limiting oxygen index value; UL-94 represents the vertical burning rating Analysis of the data in Table 3 shows that after the thermal shock test, the limiting oxygen index of the green bio-based composite flame retardant coatings prepared in Example 3 and Control Examples 1-2 decreased, but the decrease was controlled within 10%, indicating that the bonding strength between the coating and the substrate was relatively high.
[0038] Figure 3(a) Heat release rate of FPUF prepared by DCS / DEL / 3APP / MMT in Example 3; (b) Total heat release of FPUF prepared by DCS / DEL / 3APP / MMT in Example 3; (c) Smoke release rate of FPUF prepared by DCS / DEL / 3APP / MMT in Example 3; (d) Total smoke release of FPUF prepared by DCS / DEL / 3APP / MMT in Example 3. Test conditions: sample size (100×100×25) mm. 3 , the radiation intensity is 35kJ / m 2 The figure shows that the polyurethane foam coated with DCS / DEL / 3APP / MMT performs better than blank polyurethane foam in terms of heat release rate, total heat release, smoke release rate, and total smoke release. Cone calorimetry results demonstrate that the green bio-based composite flame retardant coating effectively suppresses the combustion of polyurethane foam, demonstrating its potential for application in flame retardancy.
[0039] In summary, the green bio-based composite flame retardant coatings prepared in Examples 1-4 of the present application have excellent flame retardant effects, especially the green bio-based composite flame retardant coating prepared in Example 3 of the present application has the best effect. The best implementation method of the present application is Example 3.
[0040] The above content is merely an example and explanation of the concept of the present application. Technicians in this technical field may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present application.
Claims
1. A method for preparing a green bio-based composite flame retardant coating, characterized in that: The following steps are involved: S1. dissolving p-hydroxybenzaldehyde in tetrahydrofuran, then adding triethylamine, transferring the mixture into a reactor, and then dropwise adding diphenyldichlorosilane into the reactor, stirring, filtering, and rotary evaporation to obtain 4,4'-(diphenylsilanediyl)bis(oxy)dibenzaldehyde; S2, adding chitosan to methanol, stirring, then adding 4,4'-(diphenylsilanediyl)bis(oxy)benzaldehyde, heating and stirring, then cooling, filtering, washing, and drying to obtain modified chitosan; S3, adding the modified chitosan to deionized water, adjusting the pH, stirring, heating, and then adding gelatin and stirring to obtain a modified chitosan / gelatin mixed solution; S4, adding ammonium polyphosphate to anhydrous ethanol, ultrasonicating, stirring, and then adding to the modified chitosan / gelatin mixture, heating and stirring to obtain a mixture A; S5. Dispersing sodium montmorillonite in deionized water, ultrasonicating and stirring to obtain dispersion B; S6. Add the dispersion B to the mixed solution A, heat, stir, and allow to stand to obtain a green bio-based composite flame retardant coating.
2. The method for preparing a green bio-based composite flame retardant coating according to claim 1, characterized in that: The molar ratio of the added amounts of p-hydroxybenzaldehyde and triethylamine in step S1 is 1:1-2.
3. The method for preparing a green bio-based composite flame retardant coating according to claim 1, characterized in that: The temperature of the rotary evaporation is 45-55°C.
4. The method for preparing a green bio-based composite flame retardant coating according to claim 1, characterized in that: In step S2, the molar ratio of chitosan to 4,4'-(diphenylsilanediyl)bis(oxy)benzaldehyde is 1:1-2.
5. The method for preparing a green bio-based composite flame retardant coating according to claim 1, characterized in that: The pH is adjusted to 5-6.
6. The method for preparing a green bio-based composite flame retardant coating according to claim 1, characterized in that: The heating in step S3 is to raise the temperature to 40-80°C.
7. The method for preparing a green bio-based composite flame retardant coating according to claim 1, characterized in that: The total mass of the modified chitosan and ammonium polyphosphate accounts for 7-9% of the green bio-based composite flame retardant coating in terms of mass ratio, wherein the mass ratio of the modified chitosan and ammonium polyphosphate is 1:1 or 1:2 or 1:3 or 1:
4.
8. Use of the preparation method of the green bio-based composite flame retardant coating according to any one of claims 1 to 7 in polyurethane foam.
9. Use of the green bio-based composite flame retardant coating prepared according to the preparation method of the green bio-based composite flame retardant coating according to any one of claims 1 to 7 in polyurethane foam.