A method for preparing a bio-based smoke-suppressing attenuated flame-retardant coating

Abstract

The present application provides a kind of preparation method of bio-based smoke suppression attenuated flame-retardant coating, it is related to the field of wood material and polyurethane foam material flame-retardant.The present application uses wood material and polyurethane foam material as matrix, hydrolyzed collagen aqueous solution and molecular sieve are added into phytic acid aqueous solution to obtain PDF solution, by sequentially dipping CS, PDF solution to matrix, bio-based flame-retardant coating is obtained.The preparation method can be widely applied to wood material and polyurethane foam material, etc.The method of the present application can greatly improve the flame-retardant performance of matrix material, reduce the release amount of smoke and carbon monoxide, and has high transparency, green environmental protection, simple operation, low cost and other characteristics, has the application prospect of large-scale preparation.

Description

Technical Field

[0001] This invention relates to a method for preparing a bio-based smoke-suppressing, toxicity-reducing, and flame-retardant coating, and particularly to a method for preparing a halogen-free, environmentally friendly flame-retardant coating. Technical Background

[0002] Wood and polyurethane foam are two widely used lightweight materials, boasting advantages such as high strength-to-weight ratio and low price, making them extensively applied in furniture manufacturing, construction, and packaging. However, untreated wood and polyurethane foam are highly flammable. Wood has a limiting oxygen index (LOI) of only about 22%, while polyurethane foam's LIOI is even lower, at only 17-18%. Under these fire safety hazards, a fire could cause irreparable and massive losses. During a fire, the combustion of combustibles produces large amounts of particulate matter and carbon monoxide. Particulate matter not only obstructs the vision of those escaping but also, due to excessive inhalation of smoke and carbon monoxide, can cause fainting, reducing the success rate of escape. Therefore, addressing the drawbacks of flammability and toxic smoke release from wood and polyurethane foam by employing necessary flame-retardant modification methods to improve the flame-retardant properties of wood and reduce smoke release.

[0003] To eliminate the threat of fire, impregnation or coating with flame retardants to improve the flame retardant properties of substrates is widely adopted. Commonly used flame retardants include metal hydroxides, borides, and ammonium polyphosphate. While these materials offer good flame retardant effects, they are not environmentally friendly, and long-term use poses potential hazards to human health and the environment. Developing more environmentally friendly and efficient flame retardant strategies remains a challenging task. Some bio-based materials extracted from natural plants and animals, such as chitosan (CS), phytic acid (PA), tannic acid, sodium alginate, and plant and animal proteins, can not only overcome the poor environmental friendliness of traditional flame retardants but also provide abundant N and P flame-retardant elements, possessing the potential to achieve high-performance flame retardancy. However, NP-based flame retardants suffer from high smoke release during the flame retardant process. To reduce smoke release during the flame retardant process, molecular sieves are used to adsorb smoke, enhance the strength of the char layer on the substrate, and reduce smoke release.

[0004] This invention uses bio-based flame retardants as the main component to improve the flame retardant properties of the substrate, reduce the release of smoke and carbon monoxide, and reduce the risk of fire. Summary of the Invention

[0005] (1) Preparation of flame-retardant molecular sieve: A certain amount of tetrapropylammonium hydroxide, seed liquid, tetraethyl orthosilicate, and deionized water were sequentially subjected to hydrothermal reaction at a certain temperature for a certain time, denoted as solution A. A certain amount of aluminum-containing compound was added to a certain amount of deionized water and stirred for a certain time, denoted as solution B. A certain amount of growth regulator was added to a certain amount of deionized water and stirred for a certain time, denoted as solution C. Solution B was added to solution A and stirred evenly, and then solution C was added and stirred evenly to obtain mixed solution D. Solution D was transferred to a reaction vessel and subjected to hydrothermal reaction at a certain temperature for a certain time to obtain a white solid. After drying in an oven until there was no obvious moisture, it was calcined in a muffle furnace at a certain temperature for a certain time to obtain the flame-retardant molecular sieve.

[0006] (2) Adhesion of bio-based smoke-suppressing, toxicity-reducing, and flame-retardant coating onto substrate surface: A certain amount of chitosan was added to a certain amount of deionized water, and a certain amount of glacial acetic acid was added. The mixture was stirred until the chitosan was fully dissolved. The substrate was completely immersed in the chitosan solution for a certain period of time. After removing the sample, it was dried at a certain temperature until there was no obvious moisture on the surface, resulting in sample CS. A certain amount of hydrolyzed collagen and a certain amount of molecular sieve were completely dissolved in deionized water. Then, a certain amount of phytic acid solution was added and mixed evenly to obtain solution PDF. Sample CS was immersed in the above PDF solution for a certain period of time and then dried at a certain temperature until there was no obvious moisture on the surface, resulting in substrate treated with bio-based smoke-suppressing, toxicity-reducing, and flame-retardant coating.

[0007] Preferably, the seed solution in step (1) is mixed in a ratio of tetraethyl orthosilicate:tetrapropylammonium hydroxide (20-30) g:(15-20) g, with a stirring temperature of 35-45°C and a stirring time of 0.5-2 h. The homogenized mixture is then transferred to a high-pressure reactor and heated at 60-70°C for 24-96 h to synthesize the seed solution.

[0008] Preferably, the addition ratio of tetrapropylammonium hydroxide, seed liquid, tetraethyl orthosilicate and water in solution A in step (1) is (14-16)g:(10-12)g:(30-40)g:(45-60)g.

[0009] Preferably, the aluminum-containing compound in step (1) is one or a mixture of several of aluminum chloride, aluminum nitrate, aluminum sulfate, and aluminum acetate, and the amount of aluminum-containing compound added is 0.4-0.6g. The growth regulator is ethanol, ammonium fluoride, sodium fluoride, or urea, and the amount added is 5-8g.

[0010] Preferably, step (1) is carried out in the reactor for 12-24 hours at a temperature of 160-190°C. The calcination temperature in the muffle furnace is 400-600°C, and the calcination time is 3-6 hours.

[0011] Preferably, in step (1), the content of deionized water in solution B and solution C is 60-100g, and the stirring time is 0.5-5h.

[0012] Preferably, the substrate for step (2) is wood, polyurethane foam, particleboard, fiberboard, plywood, blockboard, veneer, etc.

[0013] Preferably, the molecular sieve in step (2) can be prepared in the manner of step (1), or it can be other types of commercially available molecular sieves.

[0014] Preferably, in step (2), the amount of chitosan added is 2-4g, the mass of deionized water is 200-350g, the amount of glacial acetic acid added is 1-3mL, the mass fraction of phytic acid solution is 30-50%, the mass of phytic acid solution is 200-300g, the amount of hydrolyzed collagen added is 5-10g, and the amount of molecular sieve added is 0.3-1g. The impregnation time is 1-10min, and the drying temperature is 50-60℃. Detailed Implementation

[0015] To better illustrate the technical means and preparation process of this invention, the invention will be described below with reference to specific implementation examples.

[0016] Example 1:

[0017] (1) 56g of tetraethyl orthosilicate (TEOS) and 40g of tetrapropylammonium hydroxide (TPAOH) were stirred at 35°C for 6h. Then the temperature of the solution was raised to 45°C and heated for 1h to remove the generated ethanol. The well-stirred mixture was then transferred to a high-pressure reactor at 70°C for 24h to obtain the seed solution.

[0018] 4.4 g of TPAOH, 2.5 g of seed culture, 8 g of TEOS, and 12 g of water were stirred at 35 °C for 1 h, and this solution is denoted as solution A. 0.1 g of AlCl3 was added to 20 g of deionized water and stirred for a certain period of time; this solution is denoted as solution B. 1 g of NH4F was added to 20 g of deionized water and stirred for 30 min; this solution is denoted as solution C. Solution B was added to solution A and stirred until homogeneous, then solution C was added and stirred until homogeneous to obtain a mixed solution D. Solution D was transferred to a reaction vessel and hydrothermally reacted at 170 °C for 12 h to obtain a paste-like white solid. After drying in an oven at 80 °C until no obvious moisture remained, the solid was calcined in a muffle furnace at 550 °C for 2 h to obtain a molecular sieve.

[0019] (2) Add 4g of CS to 300g of deionized water, add 2mL of glacial acetic acid, and stir vigorously to fully dissolve the CS. Immerse the poplar wood completely in the CS solution for 2min, remove the sample, and dry the sample at 60℃ until there is no obvious moisture on the surface to obtain sample CS. Dissolve 20g of hydrolyzed collagen and 0.5g of molecular sieve completely in 40g of deionized water, then add to 160g of 50wt% PA solution and mix well to obtain solution PDF. Immerse sample CS in the above PDF solution for 2min and then dry at 60℃ until there is no obvious moisture on the surface to obtain sample CPDF.

[0020] The LOI of the CPDF sample was 29.5%, which was 32.9% higher than that of untreated poplar. The pHRR, THR, and TSP were reduced by 70.8%, 74.6%, and 52.7% respectively compared to untreated poplar.

[0021] Example 2:

[0022] (1) Stir 56g TEOS and 40g TPAOH at 35℃ for 6h, then raise the temperature of the solution to 45℃ and heat for 1h to remove the generated ethanol. Then transfer the well-stirred mixture to a high-pressure reactor at 70℃ for 24h to obtain the seed liquid.

[0023] 4.4 g of TPAOH, 2.5 g of seed culture, 8 g of TEOS, and 12 g of water were stirred at 35 °C for 1 h, and this solution is denoted as solution A. 0.1 g of AlCl3 was added to 20 g of deionized water and stirred for a certain period of time; this solution is denoted as solution B. 1 g of NH4F was added to 20 g of deionized water and stirred for 30 min; this solution is denoted as solution C. Solution B was added to solution A and stirred until homogeneous, then solution C was added and stirred until homogeneous to obtain a mixed solution D. Solution D was transferred to a reaction vessel and hydrothermally reacted at 170 °C for 12 h to obtain a paste-like white solid. After drying in an oven at 80 °C until no obvious moisture remained, the solid was calcined in a muffle furnace at 550 °C for 2 h to obtain a molecular sieve.

[0024] (2) Add 4g of CS to 300g of deionized water, add 2mL of glacial acetic acid, and stir vigorously to fully dissolve the CS. Immerse the poplar wood completely in the CS solution for 2min, remove the sample, and dry the sample at 60℃ until there is no obvious moisture on the surface to obtain sample CS. Dissolve 20g of hydrolyzed collagen completely in 40g of deionized water, without adding molecular sieves, and then add it to 160g of 50wt% PA solution and mix well to obtain solution PD. Immerse sample CS in the above PD solution for 2min and then dry it at 60℃ until there is no obvious moisture on the surface to obtain sample CPD.

[0025] The LOI of the sample CPD was 29.0%, which was 30.6% higher than that of untreated poplar, and the pHRR was 30.7% lower than that of untreated poplar.

[0026] Example 3

[0027] Add 4g of CS to 300g of deionized water, add 2mL of glacial acetic acid, and stir vigorously to fully dissolve the CS. Completely immerse the poplar wood in the CS solution for 2 minutes. After removing the sample, dry it at 60℃ until there is no obvious moisture on the surface to obtain sample CS. Completely dissolve 20g of hydrolyzed collagen and 0.5g of commercially available ZSM-5 molecular sieve in 40g of deionized water, then add this solution to 160g of 50wt% PA solution and mix thoroughly to obtain solution PDF. Immerse sample CS in the above PDF solution for 2 minutes and then dry it at 60℃ until there is no obvious moisture on the surface to obtain sample CPDS.

[0028] The LOI of the CPDS sample was 29.1%, which was 31.1% higher than that of untreated poplar.

[0029] In summary, this invention achieves a flame-retardant coating through layer-by-layer self-assembly on the surface of a flammable substrate. Due to its high transparency, it not only does not affect the texture of the substrate itself, but its highly efficient flame-retardant and smoke-suppressing properties give the substrate a significant advantage at fire scenes. It also demonstrates excellent effectiveness in suppressing CO release, providing favorable conditions for escape. This invention offers advantages such as low cost, high operability, environmental friendliness, and large-scale production, expanding the application fields of wood-based and polyurethane foam materials and providing new perspectives for the functional utilization of these materials.

[0030] Specific embodiments of the present invention have been described above. However, those skilled in the art should understand that the above embodiments are intended to illustrate the principles of the invention, and the present invention is not limited to the specific embodiments. Any technical modifications made to the present invention without departing from the technology of the present invention are within the protection scope of the present invention.

Claims

1. A method for preparing a bio-based smoke-suppressing, toxicity-reducing, and flame-retardant coating, comprising the following steps: (1) Preparation of flame-retardant molecular sieve: A certain amount of tetrapropylammonium hydroxide, seed liquid, tetraethyl orthosilicate and deionized water were taken and hydrothermally reacted for a certain time under certain temperature conditions, and this was recorded as solution A; a certain amount of aluminum-containing compound was added to a certain amount of deionized water and stirred for a certain time, and this was recorded as solution B; a certain amount of growth regulator was added to a certain amount of deionized water and stirred for a certain time, and this was recorded as solution C; solution B was added to solution A and stirred evenly, and then solution C was added and stirred evenly to obtain mixed solution D. Solution D was transferred to a reaction vessel and hydrothermally reacted for a certain time under certain temperature conditions to obtain a white solid. After drying in an oven until there was no obvious moisture, it was calcined in a muffle furnace at a certain temperature for a certain time to obtain flame-retardant molecular sieve. (2) Bio-based smoke-suppressing, toxicity-reducing, and flame-retardant coating adheres to the substrate surface: a certain amount of chitosan is added to a certain amount of deionized water, and a certain amount of glacial acetic acid is added. The mixture is stirred to dissolve the chitosan completely. The substrate is completely immersed in the chitosan solution for a certain period of time. After the sample is removed, it is dried at a certain temperature until there is no obvious moisture on the surface to obtain sample CS. A certain amount of hydrolyzed collagen and a certain amount of molecular sieve are completely dissolved in deionized water. Then a certain amount of phytic acid solution is added and mixed evenly to obtain solution PDF. Sample CS is immersed in the above PDF solution for a certain period of time and then dried at a certain temperature until there is no obvious moisture on the surface to obtain the substrate after treatment with bio-based smoke-suppressing, toxicity-reducing, and flame-retardant coating. The seed solution in step (1) is mixed with tetraethyl orthosilicate: tetrapropylammonium hydroxide (20-30) g: (15-20) g in a ratio of 20-30 g: 15-20 g, and the stirring temperature is 25-45 °C for 0.5-24 h. The uniformly stirred mixture is then transferred to a high-pressure reactor and heated at 60-70 °C for 24-168 h to synthesize the seed solution. The addition ratio of tetrapropylammonium hydroxide, seed liquid, tetraethyl orthosilicate and deionized water in solution A in step (1) is (14-16) g : (10-12) g : (30-40) g : (45-60) g; The aluminum-containing compound in step (1) is one or a mixture of aluminum chloride, aluminum nitrate, aluminum sulfate, and aluminum acetate, and the amount of aluminum-containing compound added is 0.4-0.6g. The growth regulator is one or a mixture of ethanol, ammonium fluoride, sodium fluoride, and urea, and the amount added is 5-8g. The reaction time in step (1) in the reactor is 6-48 h, and the reaction temperature is 140-200℃; the calcination temperature in the muffle furnace is 400-800℃, and the calcination time is 1-8 h. In step (1), the content of deionized water in solutions B and C is 60-100 g, and the stirring time is 0.5-5 h. The substrate for step (2) is polyurethane foam, particleboard, fiberboard, plywood, or blockboard. The molecular sieve in step (2) is prepared in the manner described in step (1); In step (2), the amount of chitosan added is 2-4 g, the mass of deionized water is 200-350 g, the amount of glacial acetic acid added is 1-5 mL, the mass fraction of phytic acid solution is 10-70%, the mass of phytic acid solution is 200-500 g, the amount of hydrolyzed collagen added is 5-30 g, the amount of molecular sieve added is 0.3-3 g, the soaking time is 1-600 min, and the drying temperature is 50-60℃.

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