An organic-inorganic composite flame retardant, its preparation method and application

Abstract

This invention relates to an organic-inorganic composite flame retardant, its preparation method, and its application, comprising the following components by weight percentage: 10-40% multi-component composite flame retardant, 9-35% aluminum hydroxide, and 30-65% melamine; wherein the multi-component composite flame retardant is a complex containing phosphorus, iron, zinc, aluminum, and silicon. This invention combines multiple flame-retardant elements—phosphorus, nitrogen, zinc, iron, aluminum, and silicon—to achieve a synergistic flame-retardant effect, effectively achieving multiple effects such as flame retardancy, heat insulation, and smoke suppression, thus improving its overall performance in water-based fire-retardant coatings.

Description

Technical Field

[0001] This invention relates to the field of flame retardant materials technology, and in particular to an organic-inorganic composite flame retardant, its preparation method, and its application. Background Technology

[0002] Steel is a rapidly developing building material, favored by the construction industry due to its lightweight, high strength, and ease of construction. However, steel structures also have significant drawbacks. While steel itself is non-combustible, its relatively low fire resistance rating causes a rapid decline in its mechanical properties due to intense heating during a fire, leading to deformation and collapse, resulting in casualties and economic losses. Therefore, improving the fire resistance rating of steel structures is of great importance.

[0003] Applying fire-retardant coatings to steel structures is an effective method for fire protection. The application of fire-retardant coatings reduces the flammability of the coated material, prevents the spread of temperature and flame, and protects the structural integrity of the substrate, thereby protecting people's lives and property. Currently, fire-retardant coatings for steel structures in my country are mainly of intumescent and non-intumescent types. The fire-retardant effect of intumescent fire-retardant coatings mainly includes heat insulation, expansion and heat absorption, oxygen isolation, and the release of non-combustible gases to dilute the oxygen concentration. In the composition of fire-retardant coatings, the development and utilization of flame retardants are key factors determining the fire-retardant effect. Depending on the type of fire, flame retardant products can be divided into inorganic and organic types. Currently, inorganic flame retardants mainly suffer from low flame-retardant efficiency, generally requiring high filler content, and poor compatibility with polymers leading to a decline in the physical and chemical properties of the material, failing to achieve ideal performance. Organic flame retardants, on the other hand, are limited in application due to their tendency to produce toxic and harmful fumes upon thermal decomposition, poor environmental friendliness and safety, and high cost. Therefore, there is an urgent need to research and develop a new type of flame retardant that is environmentally friendly, has excellent performance, and is cost-effective. Summary of the Invention

[0004] The technical problem to be solved by this invention is: This invention provides an organic-inorganic composite flame retardant, its preparation method and application. This organic-inorganic composite flame retardant has excellent flame retardant and smoke suppression performance when applied to water-based fireproof coatings for steel structures. It can greatly reduce the generation of harmful gases at high temperatures and can expand 10-50 times. It has very good carbon layer strength and adhesion, and at the same time has a high char residue rate during high-temperature carbonization. It overcomes the shortcomings of existing organic flame retardants, such as high toxicity and a lot of smoke during combustion, and the poor physicochemical properties of inorganic flame retardants.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] This invention provides an organic-inorganic composite flame retardant, comprising the following components by weight percentage:

[0007] Multi-component flame retardant 10-40%, aluminum hydroxide 9-35%, melamine 30-65%;

[0008] The multi-component flame retardant is a complex containing phosphorus, iron, zinc, aluminum and silicon elements.

[0009] This invention proposes an organic-inorganic composite flame retardant that combines multiple flame-retardant elements, including phosphorus, nitrogen, zinc, iron, aluminum, and silicon, to achieve a synergistic flame-retardant effect. This effectively achieves multiple effects such as flame retardancy, heat insulation, and smoke suppression, enhancing its overall performance in water-based fire-retardant coatings. During heating, Al(OH)3 generates some water vapor to dilute the combustible heat in the gas phase. Adhering to the substrate surface, it isolates oxygen, lowers polymer temperature, reduces gas emissions, and promotes char formation, thus preventing combustion. Simultaneously, it generates a larger surface area, providing more phosphorus and nitrogen binding and dispersion sites. The interaction between iron, zinc, and silicon elements and phosphorus and nitrogen sites further enhances the flame-retardant and smoke-suppressing effects. Phosphorus, iron, and zinc elements further catalyze char formation to prevent heat transfer, while nitrogen transforms into a non-combustible gas during combustion, achieving heat absorption, oxygen isolation, and char dispersion. Silicon stabilizes the char layer and improves water resistance and compatibility with the base resin. This flame retardant can rapidly stop combustion and adsorb a large amount of smoke during heating, and its addition to fire-retardant coatings does not affect the overall mechanical properties. In addition, since the flame retardant system does not contain harmful elements such as halogens, it also has excellent environmental performance.

[0010] Preferably, the multi-component composite flame retardant comprises the following components: iron phosphate, zinc phosphate, aluminum oxide, and silicon dioxide.

[0011] Preferably, the multi-component composite flame retardant comprises the following components by weight percentage: 60% iron phosphate, 20% zinc phosphate, 10% aluminum oxide, and 10% silicon dioxide.

[0012] As can be seen from the above description, when specific flame-retardant inorganic materials are used in a specific proportion, the fire resistance limit can be effectively improved, the carbonization expansion is high, and the strength and adhesion of the carbonized layer are high.

[0013] Another aspect of the present invention provides a method for preparing an organic-inorganic composite flame retardant, comprising the following steps:

[0014] S1. Weigh out the multi-component flame retardant, aluminum hydroxide and melamine by weight percentage, grind them evenly, and set aside.

[0015] S2. Disperse melamine in an organic solvent at 30-100℃ and stir until completely dissolved;

[0016] S3. Add a multi-component composite flame retardant and aluminum hydroxide to the above solution, stir, react, and cool to room temperature. Then wash and freeze-dry the resulting precipitate to obtain the final product.

[0017] Preferably, in step S2, the organic solvent is methanol, and the amount used is 50-150 mL; the stirring rate is 500-1200 rpm, and the stirring time is 0.5-1.5 h.

[0018] Preferably, in step S3, the stirring time is 0.5-2 h; the reaction temperature is 80-120 °C; the reaction time is 6-12 h; and the freeze-drying time is 12-24 h.

[0019] The preparation method of the present invention is simple and convenient, the preparation process is controllable, there is almost no loss, and the yield is high.

[0020] Another aspect of the present invention provides the application of an organic-inorganic composite flame retardant in water-based fireproof coatings for steel structures. Detailed Implementation

[0021] The present invention will now be described in detail with reference to specific embodiments. It should be understood that the embodiments are only used to illustrate the present invention and not to limit the present invention. Any modifications or equivalent substitutions made on the basis of the present invention are within the protection scope of the present invention.

[0022] This invention provides an organic-inorganic composite flame retardant, comprising the following components by weight percentage:

[0023] Multi-component flame retardant 10-40%, aluminum hydroxide 9-35%, melamine 30-65%;

[0024] The multi-component flame retardant is a complex containing phosphorus, iron, zinc, aluminum and silicon elements.

[0025] The multi-component composite flame retardant includes the following components: iron phosphate, zinc phosphate, aluminum oxide, and silicon dioxide.

[0026] The multi-component composite flame retardant comprises the following components by weight percentage: 60% iron phosphate, 20% zinc phosphate, 10% aluminum oxide, and 10% silicon dioxide.

[0027] It is prepared by the following method:

[0028] S1. Weigh out the multi-component composite flame retardant, aluminum hydroxide and melamine by weight percentage, grind them evenly, and set aside.

[0029] S2. Disperse melamine in an organic solvent at 30-100℃ and stir until completely dissolved;

[0030] The organic solvent is methanol, and the amount used is 50-150 mL; the stirring speed is 500-1200 rpm, and the stirring time is 0.5-1.5 h.

[0031] S3. Add a multi-component composite flame retardant and aluminum hydroxide to the above solution, stir, react, and cool to room temperature. Then wash and freeze-dry the resulting precipitate to obtain the final product.

[0032] The stirring time is 0.5-2h; the reaction temperature is 80-120℃; the reaction time is 6-12h; and the freeze-drying time is 12-24h.

[0033] This invention also provides an application of an organic-inorganic composite flame retardant in water-based fire-retardant coatings for steel structures, one application method being:

[0034] At a speed of 800 rpm, water, cellulose, dispersant, ammonia, wetting agent, and defoamer are added sequentially to a dispersion vessel and stirred for 30 minutes. Then, titanium dioxide and talc are added and stirred for another 20 minutes. Next, pentaerythritol, a char-forming agent, foaming agent, ammonium polyphosphate, a dehydration catalyst, and the organic-inorganic composite flame retardant prepared in this invention are added. The speed is increased to 1000 rpm and stirred for 30 minutes to obtain a slurry. The speed is then reduced to 600 rpm, and emulsion, defoamer, film-forming aid, thickener, and preservative and mildew inhibitor are added. The mixture is stirred for another 30 minutes to obtain the final water-based fire-retardant coating.

[0035] Example 1

[0036] An organic-inorganic composite flame retardant comprises the following components by weight percentage:

[0037] Multi-component flame retardant 30%, aluminum hydroxide 20%, melamine 50%;

[0038] The multi-component composite flame retardant comprises the following components by weight percentage: 60% iron phosphate, 20% zinc phosphate, 10% aluminum oxide, and 10% silicon dioxide.

[0039] It is prepared by the following method:

[0040] S1. Weigh out the multi-component flame retardant, aluminum hydroxide and melamine by weight percentage, grind them evenly, and set aside.

[0041] S2. At 60°C, disperse melamine in 100 mL of methanol and stir at 1000 rpm for 0.5 h until completely dissolved;

[0042] S3. Add the multi-component composite flame retardant and aluminum hydroxide to the above solution, stir for 0.5 h, pour the resulting solution into a 200 mL Teflon-lined stainless steel autoclave, place it in an infrared oven at 100 °C and react for 6 h. After cooling to room temperature, wash the resulting precipitate several times with deionized water and freeze-dry for 12 h to obtain the final product.

[0043] Tests showed that the yield of the organic-inorganic composite flame retardant obtained in this embodiment was 85.5%, and the char residue at 900°C was 84.5%.

[0044] Example 2

[0045] An organic-inorganic composite flame retardant comprises the following components by weight percentage:

[0046] The composition includes 36.4% multi-component flame retardant, 9.1% aluminum hydroxide, and 54.5% melamine.

[0047] The multi-component composite flame retardant comprises the following components by weight percentage: 60% iron phosphate, 20% zinc phosphate, 10% aluminum oxide, and 10% silicon dioxide.

[0048] It is prepared by the following method:

[0049] S1. Weigh out the multi-component flame retardant, aluminum hydroxide and melamine by weight percentage, grind them evenly, and set aside.

[0050] S2. At 80℃, disperse melamine in 100mL of methanol and stir at 1200rpm for 40min until completely dissolved;

[0051] S3. Add a multi-component composite flame retardant and aluminum hydroxide to the above solution, stir for 1 hour, pour the resulting solution into a 200 mL Teflon-lined stainless steel autoclave, place it in an infrared oven at 80 °C and react for 8 hours. After cooling to room temperature, wash the resulting precipitate several times with deionized water and freeze-dry for 12 hours to obtain the final product.

[0052] Tests showed that the yield of the organic-inorganic composite flame retardant obtained in this embodiment was 87.5%, and the char residue at 900°C was 85.2%.

[0053] Example 3

[0054] An organic-inorganic composite flame retardant comprises the following components by weight percentage:

[0055] The composition includes 36.4% multi-component flame retardant, 18.2% aluminum hydroxide, and 45.4% melamine.

[0056] The multi-component composite flame retardant comprises the following components by weight percentage: 60% iron phosphate, 20% zinc phosphate, 10% aluminum oxide, and 10% silicon dioxide.

[0057] It is prepared by the following method:

[0058] S1. Weigh out the multi-component flame retardant, aluminum hydroxide and melamine by weight percentage, grind them evenly, and set aside.

[0059] S2. At 70°C, disperse melamine in 100 mL of methanol and stir at 1100 rpm for 50 min until completely dissolved;

[0060] S3. Add a multi-component composite flame retardant and aluminum hydroxide to the above solution, stir for 1 hour, pour the resulting solution into a 200 mL Teflon-lined stainless steel autoclave, place it in an infrared oven at 60 °C and react for 10 hours. After cooling to room temperature, wash the resulting precipitate several times with deionized water and freeze-dry for 24 hours to obtain the final product.

[0061] Tests showed that the yield of the organic-inorganic composite flame retardant obtained in this embodiment was 86.5%, and the char residue at 900°C was 80.1%.

[0062] Example 4

[0063] An organic-inorganic composite flame retardant comprises the following components by weight percentage:

[0064] Multi-component composite flame retardant 36.4%, aluminum hydroxide 27.2%, melamine 36.4%;

[0065] The multi-component composite flame retardant comprises the following components by weight percentage: 60% iron phosphate, 20% zinc phosphate, 10% aluminum oxide, and 10% silicon dioxide.

[0066] It is prepared by the following method:

[0067] S1. Weigh out the multi-component flame retardant, aluminum hydroxide and melamine by weight percentage, grind them evenly, and set aside.

[0068] S2. At 50°C, disperse melamine in 100 mL of methanol and stir at 1100 rpm for 50 min until completely dissolved;

[0069] S3. Add a multi-component composite flame retardant and aluminum hydroxide to the above solution, stir for 2 hours, pour the resulting solution into a 200 mL Teflon-lined stainless steel autoclave, place it in an infrared oven at 90°C and react for 12 hours. After cooling to room temperature, wash the resulting precipitate several times with deionized water and freeze-dry for 24 hours to obtain the final product.

[0070] Tests showed that the yield of the organic-inorganic composite flame retardant obtained in this embodiment was 80.5%, and the char residue at 900°C was 79.4%.

[0071] Example 5

[0072] An organic-inorganic composite flame retardant comprises the following components by weight percentage:

[0073] Multi-component flame retardant 33.3%, aluminum hydroxide 33.3%, melamine 33.4%;

[0074] The multi-component composite flame retardant comprises the following components by weight percentage: 60% iron phosphate, 20% zinc phosphate, 10% aluminum oxide, and 10% silicon dioxide.

[0075] It is prepared by the following method:

[0076] S1. Weigh out the multi-component flame retardant, aluminum hydroxide and melamine by weight percentage, grind them evenly, and set aside.

[0077] S2. At 60°C, disperse melamine in 100 mL of methanol and stir at 1100 rpm for 50 min until completely dissolved;

[0078] S3. Add a multi-component composite flame retardant and aluminum hydroxide to the above solution, stir for 2 hours, pour the resulting solution into a 200 mL Teflon-lined stainless steel autoclave, place it in an infrared oven at 90°C and react for 12 hours. After cooling to room temperature, wash the resulting precipitate several times with deionized water and freeze-dry for 18 hours to obtain the final product.

[0079] Tests showed that the yield of the organic-inorganic composite flame retardant obtained in this embodiment was 86.0%, and the char residue at 900°C was 76.5%.

[0080] Comparative Example 1

[0081] Weigh out 18.2% AlPO4, 9.1% ZnO, 9.1% Fe2O3, 9.1% SiO2, and 54.5% melamine, and grind them evenly. Disperse the melamine in 100 mL of methanol at 80 °C and stir at 1200 rpm for 40 min until completely dissolved. Add AlPO4, ZnO, Fe2O3, and SiO2 to the above solution and stir for 1 h. Pour the resulting solution into a 200 mL Teflon-lined stainless steel autoclave and place it in an infrared oven at 80 °C for 8 h. After cooling to room temperature, wash the resulting precipitate several times with deionized water and freeze-dry for 12 h.

[0082] The test results showed that the yield of the composite flame retardant obtained in this comparative example was 65.0%, and the char residue at 900℃ was 74.0%.

[0083] Comparative Example 2

[0084] Weigh out 80% of the multi-component flame retardant and 20% of aluminum hydroxide, grind them evenly, then disperse them in 100 mL of methanol and stir at 1200 rpm for 1 h. Pour the resulting solution into a 200 mL Teflon-lined stainless steel autoclave and place it in an infrared oven at 80 °C for 8 h. After cooling to room temperature, wash the resulting precipitate several times with deionized water and freeze-dry for 12 h.

[0085] The yield of the inorganic flame retardant obtained in this comparative example was 88.0% according to the test results.

[0086] Comparative Example 3

[0087] Weigh out 36.4% ferric phosphate, 9.1% aluminum hydroxide, and 54.5% melamine, and grind them evenly. Disperse the melamine in 100 mL of methanol at 80 °C and stir at 1200 rpm for 40 min until completely dissolved. Add ferric phosphate and aluminum hydroxide to the above solution and stir for 1 h. Pour the resulting solution into a 200 mL Teflon-lined stainless steel autoclave and place it in an infrared oven at 80 °C for 8 h. After cooling to room temperature, wash the resulting precipitate several times with deionized water and freeze-dry for 12 h.

[0088] The test results showed that the yield of the composite flame retardant obtained in this comparative example was 84.0%, and the char residue at 900℃ was 83.0%.

[0089] The flame retardants prepared in Example 2 and Comparative Examples 1-3 were applied to the preparation of water-based fire-retardant coatings, and their performance was tested. The results are recorded in Table 1.

[0090] Table 1

[0091]

[0092]

[0093] As shown in Table 1, when the addition amount of Example 2 is 10%, it exhibits the longest flame retardant time and the best smoke suppression effect when applied to fire-retardant coatings. This indicates that the organic-inorganic composite flame retardant prepared in this invention can produce excellent flame retardant effects with a small dosage, and at a low cost. A comparison of Example 2 and Comparative Example 1 shows that the flame retardant prepared by this invention through the optimal combination of compounds containing specific flame-retardant elements such as phosphorus, nitrogen, zinc, iron, aluminum, and silicon can effectively improve the flame retardant and smoke-suppressing effects and water resistance of coatings, while also achieving a high char residue rate. Comparing Example 2 and Comparative Example 2, it is evident that the introduction of melamine enables the release of uniformly dispersed non-combustible gases during the expansion of the char layer, resulting in a superior flame-retardant effect. Furthermore, because this invention employs a chemical composite method utilizing melamine to coat inorganic materials, melamine can be uniformly dispersed on the surface of aluminum hydroxide and the multi-component composite flame retardant, overcoming the problem of uneven dispersion inherent in mechanical physical mixing and significantly enhancing the synergistic effect between the organic-inorganic composite flame retardants. Simultaneously, the presence of the nitrogen-containing coating layer on the surface also improves compatibility with the matrix resin. Comparative Example 3, prepared without the multi-component composite flame retardant, also exhibits a significantly reduced flame-retardant and smoke-suppressing effect compared to Example 2.

[0094] 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 the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An organic-inorganic composite flame retardant, comprising the following components by weight percentage: Multi-component flame retardant 10-40%, aluminum hydroxide 9-35%, melamine 30-65%; The multi-component composite flame retardant comprises the following components by weight percentage: 60% iron phosphate, 20% zinc phosphate, 10% aluminum oxide, and 10% silicon dioxide.

2. A method for preparing the organic-inorganic composite flame retardant as described in claim 1, comprising the following steps: S1. Weigh out the multi-component flame retardant, aluminum hydroxide and melamine by weight percentage, grind them evenly, and set aside. S2. Disperse melamine in an organic solvent at 30-100℃ and stir until completely dissolved; S3. Add a multi-component composite flame retardant and aluminum hydroxide to the above solution, stir, react, and cool to room temperature. Then wash and freeze-dry the resulting precipitate to obtain the final product.

3. The preparation method of the organic-inorganic composite flame retardant as described in claim 2, characterized in that, In step S2, the organic solvent is methanol, and the amount used is 50-150 mL; the stirring rate is 500-1200 rpm, and the stirring time is 0.5-1.5 h.

4. The preparation method of the organic-inorganic composite flame retardant as described in claim 2, characterized in that, In step S3, the stirring time is 0.5-2 h; the reaction temperature is 80-120℃; the reaction time is 6-12 h; and the freeze-drying time is 12-24 h.

5. The application of the organic-inorganic composite flame retardant as described in claim 1 in water-based fireproof coatings for steel structures.

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