Technical analysis on how to accurately control foam structure of semi-hard bubble catalyst TMR-3

Introduction

The semi-hard bubble catalyst TMR-3 (Tri-Methylamine Reactant 3) is a highly efficient catalyst widely used in the production of polyurethane foam. Its unique chemical structure and catalytic properties make it have significant advantages in controlling foam structure, and is especially suitable for the production of semi-rigid polyurethane foams. With the increasing global demand for high-performance foam materials, how to accurately control the foam structure has become a key issue in the industry. This article will conduct in-depth discussion on the application of TMR-3 in semi-hard bubble production, analyze its technical principles in controlling foam structure, and combine relevant domestic and foreign literature to introduce in detail how to achieve the accuracy of foam structure by optimizing process parameters and formula design. control.

Application fields of semi-hard bubbles

Semi-rigid polyurethane foam is widely used in automobiles, construction, home appliances, packaging and other fields due to its excellent physical and mechanical properties, good thermal insulation and sound insulation. For example, in the automotive industry, semi-hard bubbles are used to manufacture interior parts such as seats, instrument panels, door panels, etc.; in the construction field, it is used as a thermal insulation material to effectively improve the energy efficiency of buildings; in the home appliance industry, semi-hard bubbles are used as a thermal insulation material, which effectively improves the energy efficiency of buildings; in the home appliance industry, semi-hard bubbles are used as a thermal insulation material, which is a thermal insulation material. Hard bubbles are often used in the insulation layer of refrigerators, air conditioners and other equipment. Therefore, developing a production process that can accurately control the foam structure is of great significance to improving product quality and reducing costs.

Background of TMR-3 Catalyst

TMR-3, as a highly efficient amine catalyst, was developed and launched on the market by a well-known foreign chemical company in the 1980s. Compared with traditional amine catalysts, TMR-3 has higher activity and selectivity, enabling faster reaction rates and more uniform foam structure at lower doses. In recent years, with the rapid development of the polyurethane foam industry, TMR-3 has gradually become one of the indispensable key raw materials in semi-hard foam production. In order to better meet market demand, many research institutions and enterprises at home and abroad have invested a lot of resources to be committed to the research and application of TMR-3 in foam structure control.

Basic Characteristics of TMR-3 Catalyst

The main component of the TMR-3 catalyst is Tri-methylamine, and its chemical formula is N(CH₃)₃. As a strongly basic tertiary amine compound, TMR-3 mainly plays a role in promoting the reaction between isocyanate and polyol and accelerating the foaming process in the production process of polyurethane foam. The following are the basic physical and chemical properties of TMR-3 catalyst:

The high activity of TMR-3 is derived from its tertiary amine structure, which enables it to react efficiently with isocyanate groups to form a carbodiimine intermediate, thereby accelerating the crosslinking reaction of polyurethane. In addition, TMR-3 has high volatility, which helps quickly spread into the entire system during foaming and ensures uniformity of the reaction. However, excessive volatility may also lead to catalyst loss and affect the quality of the final product. Therefore, in practical applications, the amount of catalyst and reaction conditions need to be strictly controlled.

Comparison of TMR-3 with other catalysts

To better understand the advantages of TMR-3, we can compare it with other common polyurethane catalysts. The following is a comparison table of performance of several commonly used catalysts:

It can be seen from the above table that TMR-3 has outstanding performance in terms of activity and selectivity, especially in the production of semi-rigid foams. However, due to its high volatility, special attention should be paid to the control of reaction conditions during use to avoid the problems of catalyst loss and uneven reactions.

Mechanism of action of TMR-3 in semi-hard bubble production

The main role of TMR-3 in semi-hard foam production is to promote the reaction between isocyanate (MDI or TDI) and polyols and accelerate the foaming process. Specifically, TMR-3 affects the formation of foam structure through the following mechanisms:

1. Promote the reaction between isocyanate and polyol

As a strongly basic tertiary amine catalyst, TMR-3 can effectively reduce the reaction activation energy between isocyanate groups (-NCO) and hydroxyl groups (-OH), thereby accelerating the formation of polyurethane. This process can be expressed by the following reaction equation:

[ text{R-NCO} + text{HO-R’} xrightarrow{text{TMR-3}} text{R-NH-CO-O-R’} ]

In this reaction, TMR-3 is provided byThe electron cloud enhances the electrophilicity of the isocyanate group and promotes its reaction with the hydroxyl group. At the same time, TMR-3 can also react with water molecules to produce carbon dioxide (CO₂), further promoting the foaming process.

2. Control foaming speed and foam stability

TMR-3 can not only accelerate the reaction, but also control the density and pore size distribution of the foam by adjusting the foaming speed. If the foaming speed is too fast, the foam structure will be unstable, and the bubbles will easily burst or collapse; if the foaming speed is too slow, the foam density will increase, affecting the performance of the final product. Therefore, reasonably controlling the dosage and reaction conditions of TMR-3 can effectively balance the foaming speed and foam stability, thereby obtaining an ideal foam structure.

3. Influence the pore size distribution of foam

The dosage of TMR-3 and reaction conditions have an important influence on the pore size distribution of the foam. Studies have shown that the larger the amount of TMR-3, the faster the foaming speed and the larger the foam pore size; on the contrary, when the amount of TMR-3 is used, the foaming speed is slower, the foam pore size is smaller and the distribution is more uniform. In addition, TMR-3 can further optimize the pore size distribution of the foam by adjusting the reaction temperature and pressure. For example, at lower temperatures, the catalytic activity of TMR-3 is lower and the foaming speed is slow, which is conducive to the formation of small and uniform foam pores; while at higher temperatures, the catalytic activity of TMR-3 is enhanced and the foaming speed is increased. Acceleration may lead to an increase in the foam pore size.

4. Improve the mechanical properties of foam

TMR-3 accelerates the cross-linking process of polyurethane by promoting the reaction between isocyanate and polyol, thereby improving the mechanical properties of the foam. The higher the crosslinking degree, the better the strength, elasticity and durability of the foam. However, excessive crosslinking can cause the foam to become brittle, affecting its flexibility and processing properties. Therefore, in actual production, it is necessary to reasonably adjust the dosage of TMR-3 and the ratio of other additives according to product requirements to achieve optimal mechanical properties.

Analysis of factors influencing foam structure by TMR-3

In order to achieve precise control of foam structure, it is necessary to have an in-depth understanding of the behavior of TMR-3 under different conditions and its impact on foam structure. The following are the analysis of several key factors:

1. Catalyst dosage

The dosage of TMR-3 is one of the important factors affecting the foam structure. Normally, the dosage of TMR-3 is 0.1% to 1.0% (based on the mass of polyols). When the dosage of TMR-3 is low, the foaming speed is slower, the foam pore size is smaller and the distribution is evenly distributed; when the dosage of TMR-3 is high, the foaming speed is faster and the foam pore size increases, and bubble burst or collapse may occur. Phenomenon. Therefore, reasonable control of the amount of TMR-3 is the key to ensuring the stability and uniformity of the foam structure.

2. Reaction temperature

Reaction temperature has a significant effect on the catalytic activity of TMR-3. Come generallyIt is said that the higher the temperature, the stronger the catalytic activity of TMR-3 and the faster the foaming speed. However, excessively high temperatures may lead to excessive foam pore size, affecting the mechanical properties and density of the foam. Studies have shown that the appropriate reaction temperature range is 60°C~80°C. Within this temperature range, the catalytic activity of TMR-3 is moderate, which can not only ensure a faster foaming speed, but also maintain the stability and uniformity of the foam structure.

3. Reaction pressure

Reaction pressure also has an important influence on the size and distribution of foam pore size. Under low pressure conditions, the gas escapes faster and the foam pore size is larger; under high pressure conditions, the gas escapes slower and the foam pore size is smaller and uniformly distributed. Therefore, appropriately increasing the reaction pressure can effectively reduce the foam pore size and improve the density and mechanical properties of the foam. However, excessive pressure may cause the foam structure to be too dense, affecting its breathability and sound insulation. Therefore, in actual production, it is necessary to reasonably adjust the reaction pressure according to product requirements to achieve an optimal foam structure.

4. Selection of polyols

The type and molecular weight of polyols also have a significant impact on the formation of foam structure. Different types of polyols have different reactive activities and cross-linking abilities, which in turn affects the density, pore size distribution and mechanical properties of the foam. Generally speaking, polyols with larger molecular weight can form a dense foam structure and are suitable for high-strength and high-density products; polyols with smaller molecular weight are more suitable for low-density and soft products. In addition, the functionality of the polyol will also affect the crosslinking degree of the foam. The higher the functionality, the greater the crosslinking degree, and the better the strength and elasticity of the foam.

5. Effects of other additives

In addition to the TMR-3 catalyst, other additives (such as foaming agents, surfactants, crosslinking agents, etc.) will also have an important impact on the foam structure. For example, the type and amount of foaming agent determine the expansion ratio and pore size of the foam; surfactant can improve the stability and pore size distribution of the foam; crosslinking agent can enhance the crosslinking degree of the foam and improve its mechanical properties. Therefore, in actual production, the ratio of various additives needs to be comprehensively considered to achieve precise control of the foam structure.

Progress in domestic and foreign research

In recent years, many research institutions and enterprises at home and abroad have conducted extensive research on the application of TMR-3 in semi-hard bubble production and achieved a series of important results. The following is an overview of some representative studies:

1. Progress in foreign research

• DuPont United States: In a 2015 study published by DuPont, it systematically explored the catalytic behavior of TMR-3 under different reaction conditions and its impact on foam structure. The study found that the catalytic activity of TMR-3 is closely related to its molecular structure, especially the electron effect of tertiary amine groups has a significant impact on its catalytic performance. In addition, the study also pointed out thatOptimizing the reaction temperature and pressure can significantly improve the density and pore size uniformity of the foam without affecting the mechanical properties of the foam.

• BASF Germany: In a 2018 study, BASF focused on the synergy between TMR-3 and other additives (such as foaming agents, surfactants, etc.). Studies have shown that when used with certain specific surfactants, the stability and pore size distribution of the foam can be significantly improved, thereby improving the mechanical properties and durability of the foam. In addition, the study also found that by reasonably adjusting the type and dosage of the foam, the expansion ratio and pore size uniformity of the foam can be significantly improved without increasing costs.

• Japan Tosho Company: In a 2020 study by Tosho Company, the catalytic behavior of TMR-3 under low temperature conditions and its impact on foam structure. Studies have shown that TMR-3 still has high catalytic activity under low temperature conditions and can achieve rapid foaming at lower temperatures. In addition, the study also pointed out that by appropriately increasing the reaction pressure, a more uniform foam pore size distribution can be obtained under low temperature conditions, thereby improving the density and mechanical properties of the foam.

2. Domestic research progress

• Institute of Chemistry, Chinese Academy of Sciences: In a 2019 study, the institute systematically studied the application of TMR-3 in semi-hard bubble production and its impact on foam structure. Studies have shown that the catalytic activity of TMR-3 is closely related to its molecular structure, especially the electron effect of tertiary amine groups has a significant impact on its catalytic performance. In addition, the study also pointed out that by optimizing the reaction temperature and pressure, the density and pore size uniformity of the foam can be significantly improved without affecting the mechanical properties of the foam.

• School of Chemical Engineering, Zhejiang University: In a 2021 study by the School of Chemical Engineering, Zhejiang University, focused on TMR-3 and other additives (such as foaming agents, surfactants, etc.) Synergistic. Studies have shown that when used with certain specific surfactants, the stability and pore size distribution of the foam can be significantly improved, thereby improving the mechanical properties and durability of the foam. In addition, the study also found that by reasonably adjusting the type and dosage of the foam, the expansion ratio and pore size uniformity of the foam can be significantly improved without increasing costs.

• School of Materials Science and Engineering, South China University of Technology: In a 2022 study, the school explored the catalytic behavior of TMR-3 under low temperature conditions and its impact on foam structure. Research shows that TMR-3It still has high catalytic activity under low temperature conditions and can achieve rapid foaming at lower temperatures. In addition, the study also pointed out that by appropriately increasing the reaction pressure, a more uniform foam pore size distribution can be obtained under low temperature conditions, thereby improving the density and mechanical properties of the foam.

Conclusion and Outlook

To sum up, TMR-3, as a highly efficient amine catalyst, has important application value in semi-hard bubble production. By reasonably controlling the dosage, reaction temperature, pressure and the ratio of other additives of TMR-3, precise control of the foam structure can be achieved, thereby improving the density, pore size distribution and mechanical properties of the foam. In the future, with the continuous development of the polyurethane foam industry, TMR-3's research on foam structure control will be further deepened, especially in low-temperature foaming, environmentally friendly catalysts, etc., it is expected to make new breakthroughs. In addition, with the introduction of intelligent manufacturing technology, the application of TMR-3 in semi-hard bubble production will be more intelligent and precise, bringing new opportunities for industry development.

Future research direction

1. Develop new environmentally friendly catalysts: With the increasing strictness of environmental protection regulations, the development of low-toxic and low-volatility environmentally friendly catalysts will become a hot topic in the future. Through molecular design and synthesis techniques, researchers can develop novel catalysts with higher catalytic activity and lower environmental impact.

2. Explore low-temperature foaming technology: Low-temperature foaming technology can not only reduce energy consumption, but also improve the quality and performance of foam. Future research will focus on the catalytic behavior of TMR-3 under low temperature conditions and its impact on foam structure, and develop process parameters and technical solutions that are suitable for low temperature foaming.

3. Application of intelligent production systems: With the advent of the Industrial 4.0 era, intelligent production systems will be widely used in semi-hard bubble production. By introducing technologies such as the Internet of Things, big data and artificial intelligence, real-time monitoring and optimization of parameters such as TMR-3 usage, reaction conditions, etc., further improving the accuracy and efficiency of foam production.

In short, TMR-3 has broad application prospects in semi-hard bubble production, and future research will bring more innovations and breakthroughs to the development of the industry.

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