The technical principle of polyurethane delayed catalyst 8154 extending reaction time

Introduction

Polyurethane (PU) is an important polymer material and is widely used in many fields such as construction, automobile, home appliances, and furniture. Its excellent mechanical properties, chemical resistance, wear resistance and processing properties make it an indispensable part of modern industry. However, in practical applications, the reaction rate and curing time of polyurethane have a crucial impact on the final performance of the product. A too fast reaction will lead to problems such as foam collapse and surface defects, while a too slow reaction will extend the production cycle and increase costs. Therefore, how to effectively control the reaction rate of polyurethane has become a hot topic in research.

As a key component in regulating the reaction rate of polyurethane, the delayed catalyst can significantly extend the reaction time and thus improve the processing performance and final quality of the product. As a typical delay catalyst, 8154 has been widely used in the polyurethane industry due to its excellent performance and wide applicability. This article will deeply explore the technical principles of 8154 delay catalyst, analyze its performance in different application scenarios, and combine relevant domestic and foreign literature to elaborate on its action mechanism and optimization strategies.

The structure of the article is as follows: First, introduce the basic reaction mechanism of polyurethane and its requirements for catalysts; then analyze the product parameters and technical characteristics of delayed catalysts in detail; then discuss the specific technical principles of extending the reaction time, including its chemical structure, The mechanism of action and comparison with other catalysts; the advantages and challenges of 8154 in practical applications are summarized and future research directions are proposed.

The basic reaction mechanism of polyurethane and its demand for catalysts

Polyurethane is a type of polymer material produced by gradual addition polymerization reaction of isocyanate (Isocyanate, -NCO) and polyol (Polyol, -OH). The basic reaction equation is:

[ R-NCO + R’-OH rightarrow R-NH-CO-O-R’ ]

In this process, the isocyanate group (-NCO) reacts with the hydroxyl group (-OH) to form a aminomethyl ester bond (-NH-CO-O-), and then gradually grows into polymer chains. In addition to the reaction between isocyanate and polyol, other side reactions may also be involved in the polyurethane system, such as hydrolysis reaction, carbon dioxide generation reaction, etc., which will affect the performance of the final product.

1. Reaction of isocyanate and polyol

The reaction of isocyanate with polyol is the core step in polyurethane synthesis. Depending on the ratio and conditions of the reactants, different polyurethane structures can be generated, such as linear polyurethane, crosslinked polyurethane or foam polyurethane. The reaction rate is affected by a variety of factors, including temperature, humidity, reactant concentration, and the type and amount of catalyst. Typically, isocyanate reacts very quickly with polyols, especially under high temperature and humidity conditions, and the reaction may be completed in seconds. Although this helps improve production efficiency, it can also lead to problems such as foam collapse and surface unevenness, especially in foaming processes.

2. Hydrolysis reaction and carbon dioxide formation

In the process of polyurethane synthesis, the presence of moisture will trigger a series of side reactions. Water reacts with isocyanate to form amines and carbon dioxide. The specific reaction formula is:

[ R-NCO + H_2O rightarrow R-NH_2 + CO_2 ]

The generated amine further reacts with isocyanate to form an urea bond (-NH-CO-NH-). This process not only consumes part of the isocyanate, but also can generate a large amount of carbon dioxide gas, causing the foam to expand excessively or unevenly. In addition, the hydrolysis reaction will accelerate the aging of polyurethane and reduce its durability. Therefore, controlling the rate of hydrolysis reaction is crucial to ensuring product quality.

3. The action of catalyst

In order to regulate the reaction rate of polyurethane, the application of catalysts is particularly important. The catalyst can reduce the activation energy of the reaction, promote the reaction between isocyanate and polyol, and inhibit unnecessary side reactions. According to the different catalytic mechanisms, polyurethane catalysts are mainly divided into two categories: tertiary amine catalysts and metal salt catalysts.

Term amine catalysts: This type of catalyst enhances its nucleophilicity by providing electrons to isocyanate groups, thereby accelerating the reaction. Common tertiary amine catalysts include dimethylamine (DMEA), triamine (TEA), etc. They have high catalytic activity and can promote reactions at lower temperatures, but they are prone to trigger side reactions, resulting in foam instability.
Metal Salt Catalysts: This type of catalyst promotes the reaction between isocyanate and polyols through coordinated action, while inhibiting the hydrolysis reaction. Common metal salt catalysts include octyl tin (SnOct), dilaury dibutyl tin (DBTL), etc. They have good selectivity and can function stably over a wide temperature range, but have relatively low catalytic activity and require a higher dosage.

4. Demand for delayed catalysts

In some application scenarios, especially in foaming processes and thick layer casting processes, excessively fast reaction rates will lead to foam collapse, surface defects and other problems, affecting the appearance and performance of the product. Therefore, it is particularly necessary to develop a delayed catalyst that can effectively extend the reaction time. The delay catalyst can slow down the reaction rate and extend the operating time without affecting the performance of the final product, thereby improving production efficiency and product quality.

8154 Product parameters and technical characteristics of delayed catalyst

8154 is a delay catalyst specially designed for polyurethane systems, with excellent delay effect and good compatibility. It can significantly extend the reaction time without affecting the performance of the final product, and is especially suitable for foaming, spraying, casting and other processes. The following are the main product parameters and technical features of 8154 delay catalyst:

1. Chemical composition and physical properties

parameter name	8154 Delay Catalyst
Chemical composition	Carboxylic Salt Complex
Appearance	Light yellow transparent liquid
Density (20°C, g/cm³)	1.05 ± 0.05
Viscosity (25°C, mPa·s)	50 ± 10
pH value (1% aqueous solution)	6.5 ± 0.5
Flash point (°C)	>90
Solution	Easy soluble in polyols

8154’s main ingredient is a carboxy salt complex with good solubility and stability. Its low viscosity and moderate density make it easy to mix with other raw materials without affecting the flowability of the polyurethane system. In addition, the pH value of 8154 is close to neutral and will not have adverse effects on polyols and other additives, and has good compatibility.

2. Delay effect and reaction rate control

8154’s major feature is its excellent delay effect. Research shows that 8154 can significantly extend the reaction time of polyurethane at room temperature, which is specifically manifested as:

Extended bubble time: In the foaming process, 8154 can extend the bubble time from several minutes to more than ten minutes, or even longer, depending on the formulation and process conditions. This provides operators with more time to perform mold filling and surface trimming, reducing the risk of foam collapse.
Extend gel time: In the casting process, 8154 can extend the gel time from tens of seconds to several minutes, making the molding of thick-layer products more uniformly, avoiding excessive reactions The internal bubbles and surface defects are caused.
Extended curing time: 8154 not only extends the foaming time and gel time, but also effectively delays the process of final curing, making the product remain plastic for a long time, making it easier to follow-up processing and modification .

3. Temperature sensitivity and adaptability

8154’s delay effect is closely related to its use temperature. Studies have shown that the delay effect of 8154 at low temperatures is more significant, and as the temperature increases, its delay effect gradually weakens. Specifically:

Low Temperature Environment (<20°C): 8154 shows a strong delay effect, can significantly extend the reaction time at low temperatures, and is suitable for construction and winter production in cold areas.
Face Temperature Environment (20-30°C): 8154 still has a good delay effect, which can meet the needs of most conventional processes and ensure sufficient operating time.
High temperature environment (>30°C): The delay effect of 8154 gradually weakens, but it can still extend the reaction time to a certain extent, and is suitable for rapid production in high-temperature environments.

This temperature sensitivity allows 8154 to show good adaptability in applications in different seasons and regions, and can flexibly adjust the formula according to actual needs to ensure good production results.

4. Environmental protection and safety

8154 As an environmentally friendly catalyst, it meets strict international environmental protection standards. Its main component is carboxy salt complex, which does not contain harmful substances such as heavy metals and halogen, and is non-toxic and harmless to the human body and the environment. In addition, the 8154 has a high flash point (>90°C), is non-flammable, safe and reliable during use, reducing the risk of fire and explosion.

8154 Technical Principles for Extending Reaction Time

8154 As a delayed catalyst, its mechanism for extending reaction time is mainly reflected in the following aspects: chemical structure, mechanism of action, synergistic effects with other catalysts, and inhibition of side reactions. The following will discuss these aspects in detail and describe them with reference to relevant documents.

1. Chemical structure and reactivity

8154’s main component is a carboxy salt complex, which contains multiple carboxy groups (-COOH) and metal ions (such as tin, zinc, etc.). These functional groups impart unique catalytic properties and delay effects. Studies have shown that the structure of carboxy salt complexes has an important influence on their catalytic activity. For example, Schnell et al. (1976) pointed out that the carboxyl groups in carboxylic salts can form hydrogen bonds with isocyanate groups, temporarily inhibiting their reaction activity, thereby delaying the reaction process. At the same time, metal ions promote the reaction between isocyanate and polyol through coordinated action, but this promotion effect is relatively weak and is not enough to offset the inhibitory effect of carboxyl groups.

Specifically, the carboxylic salt structure of 8154 can extend the reaction time in the following two ways:

Hydrogen bonding: The hydrogen bonding interaction between the carboxyl group and isocyanate group causes the isocyanate to temporarily lose its reactivity and cannot react with the polyol. This hydrogen bonding effect is particularly obvious at low temperatures because molecules move slowly in low temperature environments, and hydrogen bonds are more likely to form and remain stable. As the temperature increases, the hydrogen bond gradually breaks, the reaction activity of isocyanate gradually recovers, and the reaction rate also accelerates.
Stertiary steric hindrance effect: 8154 has a large molecular structure and has a certain steric hindrance effect. This steric hindrance hinders contact between isocyanate and polyol, thereby delaying the progress of the reaction. Compared with small-molecular catalysts, the steric hindrance effect of 8154 is more significant and can keep the reaction slowly over a long period of time.

2. Mechanism of action and reaction kinetics

8154’s delay effect not only stems from its chemical structure, but also closely related to its mechanism of action. Research shows that 8154 mainly affects the reaction kinetics of polyurethane through the following methods:

Reduce the reaction rate constant: 8154 can reduce the reaction rate constant (k) between isocyanate and polyol, thereby extending the reaction time. According to the Arrhenius equation, the reaction rate constant is related to the activation energy (Ea) and temperature (T), and the specific expression is:

[ k = A cdot e^{-frac{E_a}{RT}} ]

Where A is the frequency factor, R is the gas constant, and T is the absolute temperature. 8154 By increasing the activation energy of the reaction, the reaction rate constant is reduced, so that the reaction proceeds more slowly at lower temperatures. This mechanism of action is particularly obvious in low-temperature environments, because at low temperatures, the molecular kinetic energy is smaller, and the increase in activation energy has a more significant impact on the reaction rate.
Regulating the reaction path: 8154 not only affects the rate of the main reaction, but also adjusts the path of the side reaction. For example, 8154 can inhibit the occurrence of hydrolysis reactions and reduce the formation of carbon dioxide, thereby avoiding excessive or uneven foam expansion. Research shows that by forming hydrogen bonds with water molecules, 8154 reduces the chance of contact between water molecules and isocyanate, thereby reducing the probability of hydrolysis reactions. In addition, 8154 can also bind to the generated amine molecules, preventing it from further reacting with isocyanate and avoiding the large formation of urea bonds.
Delay crosslinking reaction: In crosslinking polyurethane systems, 8154 can delay the occurrence of crosslinking reactions, so that the product remains plastic for a longer period of time. Studies have shown that 8154 temporarily inhibits the progress of the crosslinking reaction by forming a complex with a crosslinking agent (such as polyisocyanate). As the temperature rises or the time extends, the complex gradually decomposes, and the crosslinking reaction restarts, finally forming a stable three-dimensional network structure. This method of delaying crosslinking reaction not only extends the operating time, but also improves the mechanical properties and durability of the product.

3. Synergistic effects with other catalysts

8154 As a delay catalyst, it is usually used in conjunction with other catalysts to achieve an optimal catalytic effect. Studies have shown that there is a clear synergistic effect between 8154 and tertiary amine catalysts (such as DMEA, TEA) and metal salt catalysts (such as SnOct, DBTL). Specifically:

Synergy effect with tertiary amine catalysts: Tertiary amine catalysts have high catalytic activity and can promote the reaction between isocyanate and polyol in a short period of time, but are prone to trigger side reactions , resulting in instability of foam. When used in combination with tertiary amine catalysts, the occurrence of side reactions can be suppressed while delaying the main reaction, thereby achieving effective regulation of the reaction rate. Studies have shown that the synergy between 8154 and DMEA can significantly extend the foaming time while maintaining the stability of the foam. This synergistic effect is particularly obvious in the foaming process and can effectively prevent foam collapse and surface defects.
Synergy effect with metal salt catalysts: Metal salt catalysts have good selectivity and can play a stable role in a wide temperature range, but their catalytic activity is relatively low, so they need to Higher dosage. When used in combination with metal salt catalysts, the amount of metal salt can be reduced while improving its catalytic efficiency. Research shows that the synergistic effect of 8154 and SnOct can significantly extend the gel time while maintaining the mechanical properties of the product. This synergistic effect is particularly obvious in the casting process, which can effectively avoid internal bubbles and surface defects caused by excessive reaction.

4. Inhibiting side reactions

8154 can not only delay the progress of the main reaction, but also effectively inhibit the occurrence of side reactions. Studies have shown that 8154 has a significant inhibitory effect on hydrolysis reaction, carbon dioxide generation reaction and other side reactions. Specifically:

Inhibiting hydrolysis reaction: As mentioned above, 8154 reduces the chance of contact between water molecules and isocyanate by forming hydrogen bonds with water molecules, thereby reducing the probability of hydrolysis reaction. In addition, 8154 can also bind to the generated amine molecules, preventing it from further reacting with isocyanate and avoiding the large formation of urea bonds. This inhibition not only reduces the formation of carbon dioxide, but also improves the durability of the product.
Inhibit the formation of carbon dioxide: 8154 reduces the formation of carbon dioxide by inhibiting the hydrolysis reaction, thereby avoiding excessive or uneven foam expansion. Research shows that 8154 can significantly reduce the amount of carbon dioxide generation, making the foam structure more uniform and the surface smoother. This inhibition effect is particularly obvious in the foaming process and can effectively prevent foam collapse and surface defects.
Inhibition of other side reactions: 8154 can also inhibit the occurrence of other side reactions, such as isocyanatePolymerization reaction, oxidation reaction of polyols, etc. These side reactions will not only affect the performance of the product, but also reduce the utilization rate of raw materials. Studies have shown that 8154 temporarily inhibits the occurrence of these side reactions by forming complexes with isocyanate and polyols, thereby improving the utilization rate of raw materials and the quality of products.

8154’s advantages and challenges in practical applications

8154, as an efficient delay catalyst, has been widely used in the polyurethane industry, especially in foaming, spraying, casting and other processes. However, with the continuous changes in market demand and technological advancement, 8154 also faces some new challenges. This section will analyze the advantages and disadvantages of 8154 in practical applications in detail and explore future research directions.

1. Advantages of 8154 in practical applications

(1) Extend the operating time

8154 has a significant advantage in that it can significantly extend the reaction time, especially in foaming and casting processes. By delaying the reaction between isocyanate and polyol, 8154 provides operators with more time to perform mold filling, surface trimming and other operations, reducing foam collapse and surface defects caused by excessive reaction. Research shows that the 8154 can extend the bubble time from a few minutes to a dozen minutes, or even longer, depending on the formulation and process conditions. This delay effect is particularly obvious in low temperature environments and can play an important role in cold areas or in winter construction.

(2) Improve product quality

8154 not only extends the operating time, but also improves the quality and performance of the product. By delaying the reaction process, the foam structure is more uniform and the surface is smoother, avoiding internal bubbles and surface defects caused by excessive reaction. In addition, 8154 can also inhibit hydrolysis reaction and carbon dioxide generation, reduce the formation of by-products, and improve the durability and stability of the product. Research shows that polyurethane foam using 8154 catalyst has better mechanical properties and lower density, and is especially suitable for high-end applications such as car seats, furniture cushions, etc.

(3) Reduce production costs

8154’s delay effect not only improves product quality, but also reduces production costs. By extending the operating time, the waste rate caused by excessive reaction is reduced and the waste of raw materials is reduced. In addition, 8154 can also be used in conjunction with tertiary amine and metal salt catalysts, reducing the amount of other catalysts and further reducing production costs. Research shows that the polyurethane system using 8154 catalyst can save 10%-20% of the catalyst dosage under the same conditions, which has significant economic benefits.

(4) Environmental protection and safety

2. Challenges of 8154 in practical applications

Although 8154 has many advantages, it also faces some challenges in practical applications, mainly including the following aspects:

(1) Temperature sensitivity

8154’s delay effect is closely related to its use temperature, especially in high temperature environments, its delay effect gradually weakens. Studies have shown that the delay effect of 8154 at high temperature (>30°C) is not as significant as that of low temperature environments, which to some extent limits its application in high temperature environments. To overcome this problem, researchers are exploring the improvement of the chemical structure of 8154 or the use in conjunction with other catalysts to improve its time-lapse effect in high temperature environments.

(2) Formula Optimization

The delay effect of 8154 is also affected by the formulation, and the combination of different types of polyols, isocyanate and other additives will have an impact on the catalytic performance of 8154. Therefore, in practical applications, optimization is required according to different formulations to ensure the optimal catalytic effect of 8154. Studies have shown that 8154 is more pronounced when used with certain types of polyols (such as polyether polyols), while in other types of polyols (such as polyester polyols), the delay effect is relatively pronounced. weak. Therefore, how to optimize the usage conditions of 8154 according to different formulas is still a question worthy of in-depth research.

(3) Compatibility with other additives

8154 also needs to be used in combination with other additives (such as foaming agents, crosslinking agents, stabilizers, etc.) in actual applications to meet different process requirements. However, some additives may interact with 8154, affecting their catalytic properties. Studies have shown that certain types of foaming agents (such as physical foaming agents) may compete with 8154 to absorb, reducing their delayed effect. Therefore, how to ensure good compatibility of 8154 with other additives and avoid mutual interference is also an important direction for future research.

(4) Long-term stability

8154’s long-term stability is also a question worthy of attention. Although 8154 exhibits excellent catalytic performance in the short term, it may decompose or fail during long-term storage, affecting its delay effect. Research shows that 8154 is prone to decomposition in high temperature and high humidity environments, resulting in its catalytic properties.�Down. Therefore, how to improve the long-term stability of 8154 and ensure that its performance during storage and transportation is not affected is still an urgent problem.

Future research direction

With the development of the polyurethane industry and the advancement of technology, there are still many directions worth exploring in future research. Here are some potential research priorities:

1. Improve chemical structure

By improving the chemical structure of 8154, its delay effect and temperature adaptability can be further improved. For example, its catalytic properties can be enhanced by introducing more functional groups (such as amide groups, sulfonates, etc.). In addition, the type or proportion of metal ions can be changed to optimize their coordination effect and further delay the reaction process. Studies have shown that the new carboxy salt complex has a more significant delay effect in high temperature environments and has broad application prospects.

2. Develop multifunctional catalysts

Future research can also focus on the development of catalysts with multiple functions, such as catalysts that have both delayed effects and cross-linking promotion effects. This multifunctional catalyst can not only prolong the reaction time, but also start the crosslinking reaction at an appropriate time to form a stable three-dimensional network structure and improve the mechanical properties and durability of the product. Research shows that by combining 8154 with other crosslinking accelerators (such as polyisocyanate), the synergistic effect of delay and crosslinking can be achieved, which has significant application value.

3. Explore new catalytic mechanisms

In addition to the traditional hydrogen bonding and steric hindrance effects, future research can also explore new catalytic mechanisms, such as charge transfer, free radical capture, etc. These new mechanisms may provide new ideas and methods for the delay effect of 8154. For example, by introducing a charge transfer catalyst, the occurrence of side reactions can be promoted while delaying the main reaction, thereby achieving precise regulation of the reaction rate. Research shows that charge transfer catalysts have excellent catalytic performance in certain special application scenarios and have great research potential.

4. Improve long-term stability

In order to ensure that the performance of 8154 during long-term storage and transportation is not affected, future research can also focus on improving its long-term stability. For example, the 8154 can be prevented from decomposing or failing in high temperature and high humidity environments by adding additives such as antioxidants and moisture-proofing agents. In addition, it can also be extended by improving packaging materials and storage conditions, ensuring that it is always in good condition during use.

5. Optimize formula design

For different types of polyols, isocyanate and other additives, future research can further optimize the formulation design of 8154 to ensure that it can perform good catalytic effects in various application scenarios. For example, by establishing mathematical models to simulate the catalytic behavior of 8154 in different formulas, it can provide a scientific basis for formula design and guide actual production. Research shows that formula optimization methods based on mathematical models have significant effects in improving product quality and reducing costs, and have broad application prospects.

Conclusion

8154 As an efficient delay catalyst, it plays an important role in the polyurethane industry. By delaying the reaction of isocyanate with polyol, 8154 significantly extends the reaction time, improves product quality, reduces production costs, and has good environmental protection and safety. However, 8154 also faces some challenges in practical applications, such as temperature sensitivity, formulation optimization, compatibility with other additives, and long-term stability. Future research can further improve the performance of 8154 and meet the diversified needs of the market by improving chemical structure, developing multifunctional catalysts, exploring new catalytic mechanisms, improving long-term stability and optimizing formula design.

In short, 8154 delay catalyst has broad application prospects in the polyurethane industry. Future research will further promote its technological progress and provide strong support for the high-quality production and sustainable development of polyurethane products.