Polyurethane soft foam plastic is a key product in the polyurethane industry, requiring the use of organic amine catalysts, particularly organic tertiary amine catalysts. These catalysts are crucial for the main reactions in polyurethane foam formation: the reactions of carbon dioxide and molecular polymerization. They facilitate the rapid expansion of reaction mixtures, increase viscosity, and significantly boost polymer molecular weight. These conditions are vital for foam formation, ensuring that soft foam plastics possess properties like low density, high strength-to-weight ratio, high resilience, and comfort. Among the various types of organic amine catalysts used for polyurethane soft foam plastics, triethylene diamine (TDEA) and bis(dimethylaminoethyl) ether (known as A1) are highly efficient and widely used.
Due to differences in molecular structure between TDEA and A1 catalysts, their catalytic performances differ significantly, especially in reactions involving carbon dioxide gas and molecular polymerization. Failure to account for these differences during production can result in substandard foam products or difficulty in foam formation. Understanding and mastering the performance differences between these catalysts in polyurethane foam production is therefore crucial. TDEA is solid under normal conditions, making it less convenient to use. In production, it is typically dissolved in low molecular weight alcohol compounds to create a 33% solution, referred to as A33. A1, in contrast, is a low-viscosity liquid that can be directly applied. Below is a comparison of the catalytic performance differences between A1 and A33 in producing polyurethane soft foam plastics.
A33 has a 60% catalytic function for carbon dioxide gas reactions and a 40% function for molecular polymerization. Its effective utilization rate of carbon dioxide gas is low, resulting in lower foaming height and higher foam density. With most catalytic function used for molecular polymerization, A33 tends to produce closed-cell foam bodies that are stiff with low rebound, and the adjustable range of tin catalysts is narrower. To achieve the same catalytic function, A33 usage is 33% more than A1. Both the bottom and outer skins of the foam body are thicker. Increasing the amount of A33 can speed up the reaction, but the tin catalyst amount must be reduced accordingly to avoid producing closed-cell foam bodies.
A1 has an 80% catalytic function for carbon dioxide gas reactions and a 20% function for molecular polymerization. Its high effective utilization rate of carbon dioxide gas leads to higher foaming height and lower foam density. With most catalytic function used for gas generation reactions, A1 tends to produce open-cell foam bodies that are soft with high rebound, and the adjustable range of tin catalysts is wider. To achieve the same catalytic function, less A1 is needed compared to A33. Both the bottom and outer skins of the foam body are thinner. Increasing the amount of A1 can speed up the reaction, but the tin catalyst amount must be increased to prevent over-foaming and cracking.
Overall, A1 exhibits higher comprehensive catalytic performance than triethylene diamine (TDEA). Its application effects are superior, although TDEA is more convenient in terms of transportation and storage. Currently, most mechanical continuous foam production facilities predominantly use A1, while all box-type foam production facilities use TDEA. However, with a proper understanding of their differences and suitable formulation adjustments, both can be interchanged to produce high-quality foam products.
