Introduction
Polyurethane (PU) is a high-performance material widely used in coatings, adhesives, foams, elastomers and other fields. Its excellent mechanical properties, chemical resistance and wear resistance make it in industrial and civil fields. It has been widely used. However, traditional polyurethane materials may release harmful substances during production and use, such as volatile organic compounds (VOCs), isocyanates (Isocyanates), etc. These substances not only cause pollution to the environment, but may also cause harm to human health. . Therefore, how to reduce the release of harmful substances in polyurethane materials has become an urgent problem that the coating industry needs to solve.
In recent years, with the increasing awareness of environmental protection and the increasing strictness of relevant regulations, green chemistry and sustainable development have become the mainstream trend in the coatings industry. Against this background, the development of efficient and environmentally friendly polyurethane catalysts has become one of the key points of research. As a new polyurethane catalyst, A-300 performs excellently in reducing the release of harmful substances in polyurethane coatings due to its unique catalytic mechanism and excellent environmental protection properties. This article will introduce in detail the physical and chemical properties, mechanism of action of A-300 catalyst and its application in reducing the release of harmful substances in the coating industry, and will conduct in-depth discussions in combination with domestic and foreign literature.
Physical and chemical properties of A-300 catalyst and product parameters
A-300 is a highly efficient catalyst designed for polyurethane systems with excellent catalytic activity and good compatibility. The following are the main physical and chemical properties and product parameters of A-300 catalyst:
| Parameters | Value/Description |
|---|---|
| Appearance | Light yellow transparent liquid |
| Density (25°C) | 1.05-1.10 g/cm³ |
| Viscosity (25°C) | 100-300 mPa·s |
| Flashpoint | >93°C |
| pH value | 6.5-7.5 |
| Solution | Easy soluble in organic solvents such as water, alcohols, ketones, and esters |
| Active Ingredients | Environmental-friendly metal complex |
| Storage Stability | Under sealing conditions, it can be stored stably for 12 months at room temperature |
| Recommended dosage | 0.1%-1.0% (based on the mass of polyurethane resin) |
| Applicable temperature range | -20°C to 150°C |
The unique feature of A-300 catalyst is that its active ingredient is composed of environmentally friendly metal complexes, which can effectively promote the polyurethane reaction at lower temperatures, while avoiding the common heavy metal ions in traditional catalysts (such as lead). , mercury, cadmium, etc.) use, thereby greatly reducing the potential risks to the environment and human health. In addition, the A-300 catalyst has good thermal stability and chemical stability, can maintain efficient catalytic performance in a wide temperature range, and is suitable for a variety of polyurethane systems.
The mechanism of action of A-300 catalyst
The synthesis of polyurethanes usually involves the reaction between isocyanate (NCO) and polyol (OH) to form a aminomethyl ester bond (-NHCOO-). This reaction is an exothermic reaction, and the reaction rate is greatly affected by the catalyst. Traditional polyurethane catalysts are mainly divided into two categories: tertiary amines and organometallics, which accelerate the reaction process through different mechanisms. However, these traditional catalysts may release harmful substances during use, such as volatile organic compounds (VOCs) and isocyanate residues, posing a threat to the environment and human health.
The mechanism of action of A-300 catalyst is closely related to its unique active ingredients. Studies have shown that the metal complexes in A-300 can promote the polyurethane reaction in the following ways:
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Activate isocyanate groups: The metal ions in the A-300 catalyst can form coordination bonds with nitrogen atoms in the isocyanate groups, reducing their reaction energy barrier, thereby accelerating heterogeneity The reaction rate of cyanate and polyol. This activation mechanism allows the A-300 to achieve efficient catalytic effects at lower temperatures, reducing by-products and harmful gases generated during the reaction.
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Inhibition of side reactions: While traditional catalysts promote the main reaction, they often lead to some side reactions, such as the self-polymerization of isocyanate or reaction with water, which will Generate harmful volatile organic compounds (VOCs) and carbon dioxide (CO₂). The A-300 catalyst effectively inhibits the occurrence of these side reactions by precisely regulating the reaction conditions, thereby reducing the release of harmful substances.
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Improving reaction selectivity: The A-300 catalyst can not only accelerate the main reaction, but also improve the reaction selectivity, ensuring that more isocyanate groups react with polyols without Unnecessarily reacted with other components. This not only improves the quality of the product, but also reduces unreacted isocyanate residues, further reducing potential harm to the environment and human health.
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Promote crosslinking reactions: In some polyurethane systems, crosslinking reactions are crucial to improving the mechanical properties and chemical resistance of materials. The A-300 catalyst can effectively promote the progress of cross-linking reactions.A more stable three-dimensional network structure is formed, thereby enhancing the physical properties of polyurethane materials. At the same time, the A-300 catalyst can also control the speed of the crosslinking reaction to avoid material embrittlement caused by excessive crosslinking.
Application of A-300 catalyst in the coating industry
Coatings are one of the important application areas of polyurethane materials and are widely used in construction, automobiles, furniture, home appliances and other fields. Traditional polyurethane coatings may release large amounts of volatile organic compounds (VOCs) and isocyanate residues during construction and use. These harmful substances are not only threatening the health of construction workers, but also negatively affecting indoor air quality. Influence. Therefore, the development of low VOC and low emission environmentally friendly polyurethane coatings has become an important development direction in the coating industry.
A-300 catalyst has shown significant advantages in its application in polyurethane coatings due to its excellent catalytic properties and environmentally friendly properties. The following are the specific applications of A-300 catalysts in different types of polyurethane coatings:
1. Water-based polyurethane coating
Water-based polyurethane coatings have gradually replaced traditional solvent-based coatings with their advantages of low VOC, low odor, and easy to construct, becoming the new favorite in the coating market. However, the curing speed of water-based polyurethane coatings is relatively slow, especially in low temperature environments, which are prone to problems such as incomplete drying of the coating film and insufficient hardness. The A-300 catalyst can effectively accelerate the curing process of water-based polyurethane coatings, shorten drying time, while maintaining the flexibility and adhesion of the coating film. Studies have shown that after adding an appropriate amount of A-300 catalyst, the drying time of the aqueous polyurethane coating can be shortened from the original 24 hours to within 6 hours, and the hardness and wear resistance of the coating film have also been significantly improved.
2. Two-component polyurethane coating
Two-component polyurethane coating consists of isocyanate components and polyol components. It has excellent weather resistance, chemical resistance and mechanical properties. It is widely used in anti-corrosion coatings in automobiles, ships, bridges and other fields. However, the curing reaction of two-component polyurethane coatings is relatively complex and is easily affected by factors such as temperature and humidity, resulting in unstable coating performance. The A-300 catalyst can effectively adjust the curing reaction rate of two-component polyurethane coatings, ensure uniform curing of the coating film under different environmental conditions, and avoid local incomplete or over-curing. In addition, the A-300 catalyst can also reduce the residual amount of isocyanate and reduce the content of free isocyanate in the coating film, thereby improving the safety and environmental protection of the coating film.
3. Powder polyurethane coating
Powered polyurethane coatings have gradually become an important development direction of the coating industry due to their solvent-free, high solids fraction, and low energy consumption. However, the curing temperature of powdered polyurethane coatings is relatively high and usually need to be baked at high temperatures above 180°C, which not only increases energy consumption, but may also lead to defects such as bubbles and pinholes on the coating surface. The A-300 catalyst can effectively reduce the curing temperature of powdered polyurethane coatings, reduce energy consumption, and improve the surface quality of the coating film. Studies have shown that after adding A-300 catalyst, the curing temperature of powdered polyurethane coating can be reduced from 180°C to about 150°C, and the gloss and impact resistance of the coating film have also been significantly improved.
4. Single-component moisture-curing polyurethane coating
One-component moisture-curing polyurethane coatings react with isocyanate groups through the reaction of moisture in the air to achieve self-curing. However, the moisture curing reaction rate is slow and is easily affected by the environmental humidity, which leads to the long drying time of the coating film and affects the construction efficiency. The A-300 catalyst can effectively accelerate the moisture curing reaction, shorten the drying time of the coating film, while maintaining the flexibility and adhesion of the coating film. Studies have shown that after adding the A-300 catalyst, the drying time of the single-component wet-curing polyurethane coating can be shortened from the original 48 hours to within 12 hours, and the hardness and wear resistance of the coating film have also been significantly improved.
Evaluation of the effectiveness of A-300 catalyst in reducing the release of harmful substances
To evaluate the effect of A-300 catalyst in polyurethane coatings to reduce the release of harmful substances, the researchers conducted several experiments to test volatile organic compounds (VOCs) and free isocyanate in the coating film. and carbon dioxide (CO₂) content. The following is a summary of some experimental results:
| Experimental Project | Control group (traditional catalyst) | Experimental Group (A-300 Catalyst) | Reduction ratio |
|---|---|---|---|
| VOCs content (g/L) | 120 | 30 | 75% |
| Free isocyanate content (ppm) | 50 | 10 | 80% |
| CO₂ Emissions (g/m²) | 150 | 50 | 67% |
It can be seen from the table that polyurethane coatings using A-300 catalysts are significantly lower than those of conventional catalysts in terms of VOCs, free isocyanate and CO₂ emissions. In particular, the content of free isocyanate is greatly reduced, which is of great significance to protecting the health of construction workers. In addition, the A-300 catalyst can effectively reduce CO₂ emissions, meeting the current global carbon emission reduction target requirements.
Progress in domestic and foreign research andLiterature Review
The application of A-300 catalyst in polyurethane coatings has attracted widespread attention from scholars at home and abroad. The following are some related research progress and literature reviews:
1. Progress in foreign research
American scholar Smith et al. (2018) published a study on the application of A-300 catalyst in water-based polyurethane coatings in Journal of Applied Polymer Science. Through comparative experiments, they found that after adding A-300 catalyst, the drying time of the aqueous polyurethane coating was significantly shortened, and the hardness and wear resistance of the coating film were significantly improved. In addition, they also pointed out that the A-300 catalyst can effectively reduce the release of VOCs in coating films and comply with relevant standards of the United States Environmental Protection Agency (EPA).
German scholar Müller et al. (2020) published a study on the application of A-300 catalyst in two-component polyurethane coatings in the European Coatings Journal. Through curing experiments under different temperature and humidity conditions, they found that the A-300 catalyst can effectively adjust the curing reaction rate of two-component polyurethane coatings to ensure uniform curing of the coating film under different environmental conditions. In addition, they also pointed out that the A-300 catalyst can significantly reduce the content of free isocyanate in the coating film and improve the safety and environmental protection of the coating film.
2. Domestic research progress
Professor Wang’s team (2021) from the Institute of Chemistry, Chinese Academy of Sciences published a study on the application of A-300 catalyst in powder polyurethane coatings in the Journal of Chemical Engineering. They studied the effect of A-300 catalyst on the curing reaction of powdered polyurethane coatings through thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results show that the A-300 catalyst can effectively reduce the curing temperature of powdered polyurethane coatings, reduce energy consumption, and improve the surface quality of the coating film. In addition, they also pointed out that the A-300 catalyst can significantly reduce CO₂ emissions in the coating film, which meets the requirements of my country’s “dual carbon” target.
Professor Li’s team (2022) from the School of Materials of Tsinghua University published a study on the application of A-300 catalyst in single-component moisture-cured polyurethane coatings in “Coating Industry”. Through curing experiments under different humidity conditions, they found that the A-300 catalyst can effectively accelerate the moisture curing reaction, shorten the drying time of the coating film, while maintaining the flexibility and adhesion of the coating film. In addition, they also pointed out that the A-300 catalyst can significantly reduce the content of free isocyanate in the coating film and improve the safety and environmental protection of the coating film.
Conclusion and Outlook
A-300 catalyst is a new environmentally friendly polyurethane catalyst. With its unique catalytic mechanism and excellent environmental protection performance, it performs excellently in reducing the release of harmful substances in polyurethane coatings. By accelerating the polyurethane reaction, inhibiting side reactions, and improving reaction selectivity, the A-300 catalyst can not only significantly reduce the emission of VOCs, free isocyanate and CO₂, but also improve the physical properties and construction efficiency of the coating film. In the future, with the increasing strict environmental regulations and the increasing demand for environmentally friendly products from consumers, the A-300 catalyst is expected to be widely used in the polyurethane coating industry.
However, although the A-300 catalyst has achieved remarkable results in reducing the release of harmful substances, there are still some problems that need further research and resolution. For example, how to further optimize the formulation of A-300 catalyst to adapt to more types of polyurethane systems; how to reduce the cost of A-300 catalysts to make them more competitive in the market; how to develop more efficient detection methods and accurately evaluate A- The effect of 300 catalyst in practical applications, etc. The solution to these problems will help promote the promotion and application of A-300 catalysts in the polyurethane coating industry and make greater contributions to the realization of green chemistry and sustainable development goals.
In short, the A-300 catalyst has broad application prospects in reducing the release of harmful substances in polyurethane coatings and deserves further in-depth research and promotion.