Special Polyether Polyols for Non-CFC Foaming Systems

In cyclopentane, isopentane, and all-water foaming systems, solving the issue of foaming agents' solubility in polyether is crucial. This typically involves not only using specialized silicone foam stabilizers and other surfactants but also appropriately modifying the structure of the polyether. For pentane-based systems, it is necessary to improve the solubility of low-polarity alkane foaming agents in polyether. However, because the solubility of pentane-type foaming agents in polyether is inherently limited, the amount used is generally less than that in CFC or HCFC systems. A small amount of water is often used as a chemical foaming agent to compensate.

In formulations with low foaming agent usage, the high viscosity of conventional rigid foam polyether makes the resulting polyether blend too viscous, which is unsuitable for new foaming systems. Therefore, polyethers for such foaming systems must also have relatively low viscosity.

In all-water rigid foam systems, where no physical foaming agents are used, the polyether blend does not benefit from the viscosity-reducing effect of foaming agents as solvents. Thus, the viscosity of the polyether must be exceptionally low to meet the requirements of foaming equipment and processes.

In these non-CFC foaming systems, it is often necessary to use polyether polyols that differ from those used in CFC systems. A variety of polyether products are now available for alkane-based and all-water foaming systems, characterized by good compatibility with the respective foaming agents and generally lower viscosity.

Non-CFC polyether polyols are often produced using aromatic amines (e.g., toluenediamine) as initiators or as part of a mixed initiator system. For polyols used in water-based foaming systems, a certain amount of ethylene oxide (EO) chain segments is required to ensure good miscibility with water. However, excessive EO content can lead to high water absorption in the foam products, which negatively affects their thermal and moisture resistance properties.