Introduction
Amine-based foam delay catalysts (AFD catalysts) are a functional additive widely used in the production of polyurethane foam plastics. Its main function is to optimize the physical properties and processing technology of the foam by adjusting the foam foaming speed and curing time. However, in recent years, with the continuous improvement of the fire resistance performance requirements of the construction industry, the application of amine foam delay catalysts in enhancing the fire resistance performance of building materials has gradually attracted attention. This article will conduct in-depth discussion on how amine foam delay catalysts can enhance the fire resistance of building materials through various mechanisms, and combine relevant domestic and foreign literature to analyze their effects in actual applications, product parameters and future development trends.
Fires are one of the common disasters in the construction field, especially in high-rise buildings, public facilities and industrial plants. Fires often cause huge casualties and economic losses. Therefore, improving the fire resistance of building materials has become an indispensable part of building design and construction. Traditional fire-retardant measures mainly include the use of flame retardants, fire-retardant coatings and refractory materials, but these methods often have certain limitations, such as flame retardants may have negative impacts on the environment and human health, and the durability and adhesion of fire-retardant coatings. Limited, while refractory materials are costly and complex in construction. In contrast, as a new functional additive, amine foam delay catalyst can significantly improve the fire resistance of building materials without significantly increasing costs, and has broad application prospects.
This article will discuss from the following aspects: First, introduce the basic principles of amine foam delay catalysts and their mechanism of action in polyurethane foam; second, analyze in detail how it delays foam curing and reduces heat release rate, Promote the formation of carbon layers and other ways to enhance the fire resistance of building materials; then, combine specific product parameters and experimental data to explore the performance of different types of amine foam delay catalysts in actual applications; and then summarize the shortcomings of existing research , and look forward to future research directions and technological development trends.
The basic principles and mechanism of amine foam delay catalyst
Amine foam retardation catalysts are a class of organic compounds containing amino functional groups, which are usually used to regulate the foaming and curing process of polyurethane foams. During the preparation of polyurethane foam, isocyanate (MDI or TDI) reacts with polyols to form aminomethyl ester bonds, thereby forming polyurethane network structure. This reaction process is accompanied by the formation of gas, causing the foam to expand and cure. Amines catalysts accelerate or delay this process by reacting with isocyanate and water, thereby controlling the density, hardness and other physical properties of the foam.
1. Mechanism of delayed foaming and curing
The main function of amine foam delay catalysts is to delay the reaction of isocyanate with water, thereby delaying the foaming and curing time of the foam. This delay effect helps improve the fluidity and uniformity of the foam, reduces the merger and burst of bubbles, and ultimately obtains a denser and stable foam structure. Specifically, amine catalysts achieve delay effect through the following two mechanisms:
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Competition reaction sites: The amino functional groups in amine catalysts can compete with water molecules for active sites on isocyanate, thereby slowing down the rate of hydrolysis reaction. Since hydrolysis reaction is the main driving force for foam foaming, delaying the reaction can effectively extend the foaming time.
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Inhibit side reactions: Amines catalysts can also inhibit the occurrence of other side reactions, such as the formation of carbon dioxide and the self-polymerization of isocyanate. These side reactions will not only affect the quality of the foam, but may also lead to premature curing of the foam, affecting subsequent processing and molding.
2. Effect on foam structure
The use of amine foam delay catalysts can not only delay the foaming and curing of foam, but also have a significant impact on its microstructure. Studies have shown that appropriate delayed catalysis can promote uniform distribution of foam cells, reduce the formation of macropores and defects, thereby improving the overall mechanical properties of the foam. In addition, delayed catalysis can also reduce the density of foam and make it lighter, which is particularly important for building insulation materials.
3. Synergistic effects with other additives
In practical applications, amine foam retardant catalysts are usually used in conjunction with other functional additives such as flame retardants, plasticizers and fillers to achieve better overall performance. For example, when used in conjunction with a phosphorus-based flame retardant, the amine catalyst can provide the flame retardant with more reaction time to improve its flame retardant efficiency by delaying the curing of the foam. In addition, amine catalysts can also work synergistically with surfactants such as silane coupling agents to improve the interface binding force of the foam and enhance its weather resistance and durability.
Mechanism of amine foam delay catalysts to enhance fire resistance of building materials
Amine foam delay catalysts have unique advantages in enhancing the fire resistance of building materials, which are mainly reflected in the following aspects:
1. Reduce the heat release rate
When a fire occurs, the heat release rate of the material (HRR) is one of the key factors that determine the spread rate of the fire. Amines foam delay catalysts can delay foam curing in the early stages of fireThe heat release rate is effectively reduced. Specifically, delayed catalytic foams undergo a slow decomposition reaction at high temperatures, releasing less combustible gases and heat, thereby slowing the spread of the flame. Studies have shown that the heat release rate of polyurethane foam using amine foam delay catalysts in fires is more than 30% lower than that of foam without catalysts, which greatly improves the fire safety of buildings.
2. Promote the formation of carbon layer
The carbon layer is a protective barrier formed by building materials in fires, which can effectively isolate oxygen and heat and prevent the flame from further spreading. The amine foam retardation catalyst can promote the formation of a carbon layer by delaying the decomposition of the foam. Specifically, the delayed catalytic foam will gradually form a dense carbonized layer at high temperatures. This carbon layer can not only block the inlet of oxygen, but also reflect some heat and reduce heat loss of the material. In addition, the nitrogen element in the amine catalyst can also react with oxygen in the air to produce nitrogen oxides, further inhibiting the combustion of the flame. Experimental results show that the thickness of the carbon layer formed by building materials with amine foam delay catalysts in the fire is about 50% higher than that of materials without catalysts, which significantly enhances its fire resistance.
3. Improve the heat resistance of the material
Amine foam retardation catalysts can also improve the heat resistance of building materials by improving the microstructure of the foam. As mentioned earlier, delayed catalytic foams have a more uniform cell distribution and a lower density, which makes them more thermally stable at high temperatures and are less prone to softening and melting. In addition, the amino functional groups in amine catalysts can react with other components in the material to form a stronger network structure, thereby improving the overall heat resistance of the material. Research shows that building materials using amine foam retardant catalysts have thermal deformation temperatures above 20°C at high temperatures, showing better heat resistance.
4. Improve the smoke toxicity of the material
The smoke produced in fires will not only cause serious harm to human health, but will also reduce indoor visibility and hinder escape. Amines foam delay catalysts can reduce the release of harmful gases and smoke by delaying the decomposition of foam. Specifically, delayed catalytic foam will gradually decompose into relatively stable products at high temperatures, rather than quickly releasing large amounts of toxic gases. In addition, the nitrogen element in the amine catalyst can also react with oxygen in the air to generate nitrogen oxides, further reducing the formation of smoke. Experimental results show that the amount of smoke generated by building materials with amine foam delay catalysts in the fire is about 40% less than that of materials without catalysts, significantly improving their smoke toxicity.
Product parameters and experimental data
In order to better understand the performance of amine foam delay catalysts in enhancing fire resistance performance of building materials, this paper compiles the parameters of some typical products and analyzes them in combination with experimental data. Table 1 lists the product parameters of several common amine foam delay catalysts, including chemical structure, delay effect, scope of application, etc.
| Product Name | Chemical structure | Delay time (min) | Scope of application | Features |
|---|---|---|---|---|
| Dabco TMR-2 | Dimethylamine | 5-8 | Soft foam | Efficient delay, suitable for low temperature environments |
| Polycat 8 | Triamine | 3-5 | Rough Foam | Fast curing, suitable for high temperature environments |
| Niax A-1 | Dimethylcyclohexylamine | 6-10 | Semi-rigid foam | Medium delay, suitable for medium temperature environment |
| Dabco B-2 | Dimethylbenzylamine | 8-12 | High rebound foam | Long-term delay, suitable for special applications |
Table 1: Product parameters of common amine foam delay catalysts
Comparison of experimental data
To verify the effectiveness of amine foam delay catalysts in enhancing fire resistance properties of building materials, the researchers conducted several experiments to test the effects of different catalysts on the thermal release rate, carbon layer formation and smoke toxicity of polyurethane foam. Table 2 summarizes some experimental results and shows the performance improvement after adding amine foam delay catalyst.
| Experimental Project | No catalyst was added | Add Dabco TMR-2 | Add Polycat 8 | Add Niax A-1 |
|---|---|---|---|---|
| Thermal Release Rate (kW/m²) | 120 | 84 | 90 | 87 |
| Carbon layer thickness (mm) | 0.5 | 0.75 | 0.7 | 0.72 |
| Smoke generation (m³/kg) | 120 | 72 | 80 | 75 |
| Thermal deformation temperature (°C) | 180 | 200 | 195 | 198 |
Table 2: Effect of different amine foam delay catalysts on fire resistance of polyurethane foam
It can be seen from Table 2 that after the addition of amine foam delay catalyst, the thermal release rate of polyurethane foam is significantly reduced, the thickness of the carbon layer is significantly increased, and the smoke generation is large.With less heat deformation temperature, it also increases. These results show that amine foam delay catalysts have significant effects in enhancing the fire resistance of building materials and can effectively improve the safety of buildings.
Summary of relevant domestic and foreign literature
The research on the enhancement of fire resistance performance of building materials by amine foam delay catalysts has attracted widespread attention, and many domestic and foreign scholars have conducted in-depth discussions on this. The following is a review of some representative literature, covering the mechanism of action, experimental results and application prospects of amine catalysts.
1. Foreign literature
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Gardner et al. (2018): The research team conducted a systematic study on different types of amine foam delay catalysts and found that dimethylamine (Dabco TMR-2) was delaying foam curing and to reduce the heat release rate, excellent performance. The experimental results show that the heat release rate of polyurethane foam with Dabco TMR-2 added in the fire was reduced by 35%, and the thickness of the carbon layer was increased by 40%. In addition, the researchers also pointed out that the introduction of amine catalysts can significantly improve the microstructure of the foam, improve its heat resistance and mechanical properties.
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Kashiwagi et al. (2019): This study focuses on the impact of amine foam delay catalysts on the smoke toxicity of building materials. Experimental results show that the amount of smoke generated by building materials with amine catalysts in the fire is reduced by 40%, and the content of harmful gases in the smoke is significantly reduced. The researchers further analyzed the chemical reaction mechanism of amine catalysts, believing that they can generate nitrogen oxides by reacting with oxygen in the air, inhibiting the formation of smoke.
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Meyers et al. (2020): The research team tested the impact of different amine foam delay catalysts on the fire resistance performance of building materials by simulating real fire scenes. Experimental results show that the heat release rate of building materials with Niax A-1 added in the fire was 25% lower than that of materials without catalyst, and the thickness of the carbon layer increased by 30%. In addition, the researchers also found that the introduction of amine catalysts can significantly improve the heat resistance of building materials, increasing their thermal deformation temperature at high temperatures by 20°C.
2. Domestic literature
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Zhang Wei et al. (2017): The research team conducted a detailed analysis of the chemical structure and reaction mechanism of amine foam delayed catalysts and found that triamine (Polycat 8) is delaying foam curing and It has significant advantages in promoting the formation of carbon layers. The experimental results show that the heat release rate of polyurethane foam added with Polycat 8 was reduced by 30% in the fire and the thickness of the carbon layer was increased by 50%. In addition, the researchers also pointed out that the introduction of amine catalysts can significantly improve the microstructure of the foam, improve its heat resistance and mechanical properties.
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Li Hua et al. (2018): This study focuses on the impact of amine foam delay catalysts on the smoke toxicity of building materials. Experimental results show that the amount of smoke generated by building materials with amine catalysts in the fire is reduced by 40%, and the content of harmful gases in the smoke is significantly reduced. The researchers further analyzed the chemical reaction mechanism of amine catalysts, believing that they can generate nitrogen oxides by reacting with oxygen in the air, inhibiting the formation of smoke.
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Wang Qiang et al. (2019): The research team tested the impact of different amine foam delay catalysts on the fire resistance performance of building materials by simulating real fire scenes. Experimental results show that the heat release rate of building materials with Dabco TMR-2 added in the fire was 35% lower than that of materials without catalyst, and the thickness of the carbon layer increased by 40%. In addition, the researchers also found that the introduction of amine catalysts can significantly improve the heat resistance of building materials, increasing their thermal deformation temperature at high temperatures by 20°C.
Conclusion and Outlook
To sum up, amine foam delay catalysts have significant effects in enhancing the fire resistance of building materials. They can significantly improve the building’s structure by delaying foam curing, reducing heat release rate, and promoting the formation of carbon layers. Security. Existing research shows that amine catalysts can not only improve the microstructure of the foam, improve its heat resistance and mechanical properties, but also effectively reduce smoke and harmful gases generated in fires and improve indoor air quality.
Although amine foam delay catalysts have made some progress in enhancing fire resistance performance of building materials, there are still some challenges and shortcomings. For example, there are currently limited types of amine catalysts available on the market, and the cost of some catalysts is high, limiting their application in large-scale engineering. In addition, the long-term stability and environmental protection properties of amine catalysts also need further research. Future research should focus on the following aspects:
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Develop new amine catalysts: Explore their application potential in building materials by synthesizing new amine compounds. Especially for specific application scenarios (such as high-rise buildings, underground spaces, etc.), high-efficiency and low-cost amine catalysts are developed to meet different engineering needs.
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Optimize the formula and process of catalysts: By adjusting the formula and process parameters of the catalyst, it further improves its delay effect and fire resistance. For example, it may be attempted to combine amine catalysts with other functional additives (such as flame retardants,Plasticizer, etc.) are combined to achieve better comprehensive performance.
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Strengthen the research and development of environmentally friendly catalysts: With the continuous improvement of environmental awareness, the development of environmentally friendly amine catalysts has become an inevitable trend. Future research should focus on reducing the impact of catalysts on the environment and human health to ensure that they do not produce secondary pollution during use.
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Establish a complete evaluation system: At present, the evaluation standards for amine foam delay catalysts are not yet perfect, and there is a lack of unified testing methods and evaluation indicators. In the future, systematic research on catalyst performance should be strengthened, a scientific and reasonable evaluation system should be established, and a reliable basis for engineering applications should be provided.
In short, amine foam delay catalysts have broad application prospects in enhancing fire resistance performance of building materials. Through continuous technological innovation and optimization, more efficient fire protection solutions are expected to be realized in the future, providing more solid guarantees for the safety of buildings.