Overview of polyurethane foam materials
Polyurethane foam material is a polymer material with a porous structure. It is widely used in many fields such as construction, furniture, automobiles, packaging, etc. due to its excellent thermal insulation, sound insulation, cushioning and mechanical properties. The formation of polyurethane foam is a complex physical and chemical process, in which catalysts play a vital regulatory role.
Mechanism of formation of polyurethane foam
The formation of polyurethane foam involves two main chemical reactions: foaming reaction and gel reaction.
The foaming reaction refers to the process in which isocyanate (-NCO) reacts with water to generate carbon dioxide (CO₂):
R-NCO + H₂O → R-NH₂ + CO₂↑
The CO₂ gas produced by this reaction expands the mixture to form a foam structure.
The gel reaction refers to the process in which isocyanate reacts with polyol hydroxyl (-OH) to form a polyurethane chain:
R-NCO + R’-OH → R-NH-CO-O-R’
This reaction determines the final strength and mechanical properties of the foam.
Formation mechanism of open and closed cells in foam
1. Formation mechanism of open-cell foam
The formation of open-cell foam is mainly due to the fact that when the maximum pressure is generated in the bubble, the cell wall formed by the gel reaction is not strong enough to withstand the wall membrane stretching caused by the increase in gas pressure, resulting in the rupture of the bubble wall membrane and the escape of gas from the rupture. This structural feature gives open-cell foam the following characteristics:
- Good air permeability
- Excellent sound absorption performance
- Relatively low mechanical strength
- High thermal conductivity
The open cell rate (or closed cell rate) is an important indicator for measuring foam performance, which directly affects key performance parameters such as thermal conductivity, moisture permeability and dimensional stability of the foam.
2. Formation mechanism of closed-cell foam
The formation of closed-cell foam requires a faster gelation speed, which is usually achieved by using multi-functional, low molecular weight polyether polyols to react with polyisocyanates. In this system:
- The gel reaction speed is fast enough
- The strength of the cell wall increases rapidly
- The gas cannot break through the cell wall
- A foam structure dominated by closed cells is formed
Closed-cell rigid polyurethane foam is widely used in building insulation and cold storage industries due to its excellent thermal insulation performance. Its typical closed-cell rate can reach 90%-95%.
Application of MXC-37 (DMAEE) catalyst in polyurethane foam
MXC-37 (DMAEE) is an emission-free, low-odor amine catalyst with unique advantages in polyurethane foam production:
1. Product characteristics
- High foaming activity: particularly suitable for formulations with high water content
- Low odor: significantly reduces the common amine odor in foam
- Flexibility of use: can be used as a main catalyst alone or as a co-catalyst in combination with BDMAEE, etc.
2. Main application areas
- Low-density, water-foamed porous spray polyurethane foam (SPF)
- Ester-based stabilizer soft foam
- Microcellular foam
- Elastomers
- Reaction injection molding (RIM) and reinforced reaction injection molding (RRIM)
- Rigid foam packaging applications
3. Technical advantages
MXC-37 (DMAEE) can:
- Optimize the pore structure of the foam
- Improve the dimensional stability of the foam
- Improve the surface quality of the product
- Reducing Volatile Organic Compound (VOC) Emissions
Selection and Optimization of Polyurethane Catalyst
In actual production, the selection of catalysts needs to consider the following factors:
1. Reactivity: Select a catalyst with appropriate activity according to process requirements
2. Odor requirements: Low-odor catalysts should be selected for odor-sensitive applications
3. Environmental performance: Meet increasingly stringent environmental regulations
4. Cost-effectiveness: Optimize costs while ensuring performance
MXC-37 (DMAEE) has become the catalyst of choice for many high-end polyurethane foam products due to its excellent comprehensive performance, especially in applications with strict requirements on odor and environmental protection.
Conclusion
Polyurethane catalysts play a key role in the preparation of foam materials. Different types of catalysts can regulate the pore structure, physical properties and processing characteristics of the foam. As an efficient and environmentally friendly catalyst, MXC-37 (DMAEE) provides an ideal solution for polyurethane foam production, especially for foam products that require low odor and high performance. With the continuous improvement of environmental protection requirements and the continuous advancement of technology, this type of high-performance catalyst will play an increasingly important role in the polyurethane industry.
Post time: Apr-22-2025