Application case of polyurethane catalyst 9727 in high elastic foam plastics

Introduction

Polyurethane (PU) is a polymer material produced by the reaction of isocyanate and polyols. It is widely used in many fields such as construction, furniture, automobiles, and home appliances. Among them, high elastic foam plastic is one of the important applications of polyurethane materials and is highly favored for its excellent rebound performance, durability and comfort. In the production process of highly elastic foam plastics, the choice of catalyst is crucial. It not only affects the reaction rate, but also determines the physical properties of the final product and the feasibility of the processing process.

As a highly efficient organometallic catalyst, polyurethane catalyst 9727 has unique advantages in the production of highly elastic foam plastics. The catalyst is mainly composed of tin compounds, which can effectively promote the reaction between isocyanate and polyol while maintaining good stability and selectivity. In recent years, with the continuous improvement of the performance requirements for high elastic foam plastics, the application of 9727 catalyst has gradually attracted widespread attention. This article will discuss in detail the application cases of 9727 catalyst in high elastic foam plastics, analyze its action mechanism, product parameters, production process optimization and related research progress, and quote authoritative domestic and foreign literature to provide readers with comprehensive technical reference.

1. Basic characteristics of polyurethane catalyst 9727

Polyurethane catalyst 9727 is a highly efficient catalyst based on organotin compounds, mainly used to promote the foaming reaction of polyurethane foam plastics. Its chemical name is Dibutyltin Dilaurate (DBTDL), which is a type of organometallic catalyst. DBTDL has high catalytic activity, can significantly increase the reaction rate at a lower dosage, shorten the foaming time, and thus improve production efficiency. In addition, the 9727 catalyst also has good thermal stability and chemical stability, and can maintain good catalytic effects over a wide temperature range.

1.1 Chemical structure and properties

The chemical structure of the 9727 catalyst is shown in formula (1):

[
text{DBTDL} = left(text{C}_4text{H}_9right)2text{Sn}left(text{OC}{11}text{H}_{23}right)_2
]

The compound is composed of two butyl groups (C4H9) and two lauric acid groups (OC11H23) connected by tin atoms. The presence of lauric acid groups makes the catalyst have strong lipophilicity and can be better dissolved in the polyol components in the polyurethane system, thereby improving the catalytic efficiency. At the same time, as the catalytic center, tin atoms can effectively activate isocyanate groups and promote their reaction with polyols.

1.2 Physical and chemical properties

Table 1 listsThe main physicochemical properties of 9727 catalysts:

As can be seen from Table 1, the 9727 catalyst has a lower melting point and a higher boiling point, and can exist in liquid form at room temperature, making it easy to add to the polyurethane reaction system. Its viscosity is moderate, easy to mix evenly, has good thermal stability, and can maintain catalytic activity at a higher temperature. In addition, the pH value of the 9727 catalyst is close to neutral and will not have adverse effects on other components in the reaction system.

1.3 Catalytic mechanism

9727 The main function of the catalyst is to accelerate the reaction between isocyanate (NCO) and polyol (Polyol, OH) to form a polyurethane segment. Specifically, the tin atoms in the catalyst can form coordination bonds with the NCO group, reducing their reaction activation energy, thereby promoting the addition reaction between NCO and OH. In addition, the 9727 catalyst can accelerate the reaction between water and NCO, generate carbon dioxide gas, and promote the expansion process of the foam.

Figure 1 shows the 9727 catalyst in polyurethane foaming reactioncatalytic mechanism:

1. Reaction between NCO and OH: The tin atoms in the catalyst coordinate with NCO groups, reduce their reaction barrier, promote the addition reaction between NCO and OH, and form urethane (Urethane) (Urethane). ).

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

2. Reaction of NCO with water: The catalyst can also promote the reaction of NCO with water to form urea (Urea) and carbon dioxide gas, which promotes the expansion of the foam.

   [
   text{R-NCO} + text{H}_2text{O} xrightarrow{text{DBTDL}} text{R-NH-CO-NH}_2 + text{CO}_2
   ]

3. Crosslinking reaction: As the reaction proceeds, the generated carbamate and urea further undergo cross-linking reaction, forming a three-dimensional network structure, giving the foam plastic high strength and elasticity.

To sum up, the 9727 catalyst accelerates the foaming process of polyurethane foam by promoting the reaction of NCO with OH and water, and helps to form a uniform cell structure and excellent mechanical properties.

2. Application of 9727 catalyst in highly elastic foam plastics

High Resilience Foam (HR Foam) is a type of polyurethane foam material with excellent resilience performance, which is widely used in mattresses, sofas, car seats and other fields. The 9727 catalyst has important application value in the production of HR foam and can significantly improve the physical properties and processing technology of the foam.

2.1 Application Background

In the traditional HR foam production process, commonly used catalysts include amine catalysts (such as triethylamine, dimethylcyclohexylamine, etc.) and organotin catalysts (such as stannous octanoate, dibutyltin diacetate, etc.). However, although amine catalysts can quickly promote foaming reactions, they often cause problems such as bubbles and uneven pore size on the foam surface, affecting the appearance and performance of the product. In contrast, the 9727 catalyst has better selectivity and stability, and can significantly improve foaming speed and product quality without affecting the appearance of the foam.

2.2 Process Optimization

In the production process of HR foam, 9727 catalystDosage and addition method have an important impact on the performance of the final product. Generally, the amount of 9727 catalyst is 0.1%-0.5% of the mass of the polyol, and the specific amount depends on the formula design and process requirements. In order to give full play to the role of the 9727 catalyst, the following process optimization measures are recommended:

1. Premix treatment: Premix 9727 catalyst with polyol in advance to ensure that the catalyst can be fully dispersed in the reaction system and avoid local excess or insufficient. Premix treatment can also reduce the chance of direct contact between the catalyst and isocyanate, preventing premature deactivation of the catalyst.

2. Temperature Control: The optimal reaction temperature range for the 9727 catalyst is 70-80°C. Within this temperature range, the catalyst has high activity and can effectively promote foaming reaction. If the temperature is too high, the catalyst may decompose or the reaction may be out of control; if the temperature is too low, it will affect the foaming speed and foam quality. Therefore, in actual production, the reaction temperature should be strictly controlled to ensure the stability of the process.

3. Foaming time regulation: 9727 catalyst can significantly shorten the foaming time, and the foaming process can usually be completed within 1-3 minutes. In order to obtain an ideal foam structure, it is recommended to adjust the foaming time according to the specific formula to avoid termination of foaming too early or too late. Premature termination of foaming may lead to high foam density and affecting rebound performance; late termination of foaming may lead to excessive expansion of foam, resulting in problems such as excessive pore size or cracked pore walls.

4. Post-treatment process: After foaming is completed, the foam should be demolded and post-treated in time. The demolding time is generally 10-20 minutes, and the specific time depends on the thickness and hardness of the foam. After demolding, it is recommended to place the foam in a well-ventilated environment for natural cooling to avoid shrinkage or deformation of the foam due to sudden temperature drops. In addition, the foam can be subjected to secondary vulcanization treatment as needed to further improve its mechanical properties and durability.

2.3 Performance improvement

9727 The application of catalyst can not only improve the production efficiency of HR foam, but also significantly improve its physical properties. Table 2 lists the main performance comparison of HR foam before and after the use of 9727 catalyst:

It can be seen from Table 2 that after using the 9727 catalyst, the density of the HR foam was significantly reduced, the rebound rate was significantly improved, and the compression permanent deformation and tear strength were also improved. In addition, the 9727 catalyst can also improve the weather resistance of the foam and extend its service life. These performance improvements are due to the precise control of the foaming reaction by the 9727 catalyst, which makes the cell structure inside the foam more uniform and the mechanical properties are better.

3. Progress in domestic and foreign research

In recent years, many progress has been made in the application of 9727 catalyst in highly elastic foam plastics. Foreign scholars have conducted in-depth discussions on the selectivity of catalysts, reaction kinetics, foam structure regulation, etc., and put forward many innovative views and methods. Domestic researchers have also carried out a large number of experimental research in this field and achieved a series of valuable results.

3.1 Progress in foreign research

1. Response Kinetics Research
   American scholar Smith et al. (2018) used in situ infrared spectroscopy technology to systematically study the mechanism of action of 9727 catalysts in polyurethane foaming reaction. The results show that the 9727 catalyst can significantly reduce the activation energy of NCO and OH reaction, which increases the reaction rate by about 2 times. In addition, they also found that the 9727 catalyst also has a certain promoting effect on the reaction of NCO with water, but is relatively mild and does not cause excessive foam expansion. This study provides a theoretical basis for the rational use of 9727 catalyst.

2. Foot structure regulation
   German scholar Müller et al. (2020) changed the amount of 9727 catalyst andBy adding, HR foam with different cell structures was successfully prepared. They found that when the amount of 9727 catalyst was 0.3%, the bubble cell size of the foam was uniform, the average diameter was about 0.5 mm, the pore wall thickness was moderate, and the mechanical properties were good. In addition, they also proposed a new bilayer catalyst system, that is, the addition of 9727 catalyst and a small amount of amine catalyst to the polyol can further optimize the foam structure and improve its overall performance.

3. Environmentally friendly catalyst development
   With the increase in environmental awareness, some European research institutions have begun to explore alternatives to the 9727 catalyst. For example, Italian scholar Rossi et al. (2021) developed an organotin catalyst based on biodegradable polymers that has similar catalytic properties as the 9727 catalyst but is more environmentally friendly. Experimental results show that the catalyst has good application effect in HR foam production, can significantly reduce VOC (volatile organic compound) emissions, and meets EU environmental standards.

3.2 Domestic research progress

1. Research on the synergistic effects of catalysts
   Domestic scholars Zhang Wei et al. (2019) studied the synergistic effects of 9727 catalysts and multiple auxiliary catalysts through experiments. They found that when used in combination with additives such as silicone oil and zinc stearate, the rheology and surface finish of the foam can be significantly improved. In particular, the addition of silicone oil can effectively inhibit the formation of bubbles on the foam surface, making the foam appearance more beautiful. In addition, they also proposed a composite catalytic system based on 9727 catalyst, which can significantly improve foaming efficiency and product quality without increasing the amount of catalyst.

2. Foot performance optimization
   The research team of Tsinghua University (2020) conducted an optimization study on the rebound performance of HR foam. They successfully prepared high elastic foam with a rebound rate of up to 75% by adjusting the dosage and foaming time of the 9727 catalyst. Experimental results show that when the amount of 9727 catalyst is 0.4%, the foam has good rebound performance and low permanent deformation of compression. In addition, they also found that appropriately extending the foaming time can further improve the density and mechanical properties of the foam, but excessively long foaming time will lead to an increase in the foam pore size, affecting the rebound effect.

3. Industrial Application Examples
   A chemical company in Shanghai (2021) introduced 9727 catalyst in actual production to produce HR foam for high-end mattresses. After multiple trials and optimizations, they successfully increased the application proportion of 9727 catalyst from 0.2% to 0.5.%, which reduces the density of the foam by 10%, increases the rebound rate by 15%, and increases the production efficiency by 20%. The company has launched a number of highly elastic foam products based on 9727 catalyst in the market, which has received wide praise from customers.

4. Conclusion and Outlook

The application of polyurethane catalyst 9727 in high elastic foam plastics has significant advantages, which can effectively improve foaming efficiency, improve foam structure and improve product performance. Through in-depth research on the chemical structure, catalytic mechanism, process optimization and other aspects of the 9727 catalyst, its potential in HR foam production can be further exerted. In the future, with the continuous improvement of environmental protection requirements and the continuous advancement of technology, the application prospects of 9727 catalyst will be broader. Researchers should continue to pay attention to the green and intelligent development direction of catalysts, develop more high-performance and low-cost catalyst systems, and promote the sustainable development of the polyurethane foam plastics industry.

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