trans-1,2-Dichloroethylene as an Additive for HFC-134a Foam Systems

HFC-134a has been used as a zero ozone depletion potential (ODP) alternative for HCFC-141b in polyurethane foam applications. Between two major categories of zero ODP alternatives, hydrocarbons and HFCs, HFC-134a offers some advantages. It is nonflammable, widely available, and it is less expensive than other HFCs. It is an ideal choice for foam applications where nonflammability, volatile organic compounds (VOCs), and blowing agent costs are major issues. Yet, HFC-134a suffers from one significant drawback - it has limited solubility in polyurethane raw materials, such as polyols. Although the issue can be alleviated by careful selection of polyols and use of coblowing agents, such as water, there is a need to further improve the system. trans-1,2-Dichloroethylene (TDCE) is a liquid at room temperature (b.p. 48 C). It has no ozone depletion potential1 (ODP), and it has very low global warming potential (GWP) because it has very short atmospheric lifetime. Previously, we found that the addition of TDCE in HFCs-based urethane foam formulations significantly improved the fire performance. In this study, we evaluated the effect of TDCE on the vapor pressure of several HFC-134a-polyol combinations. The results show that the presence of TDCE can reduce the vapor pressure of certain HFC-134a-polyol blends. More importantly, the presence of TDCE allows one to reduce the levels of HFC-134, significantly reducing the overall vapor pressure of HFC-134a-containing systems. Finally, the presence of TDCE can dramatically reduce the viscosity of HFC-134a-polyols blends, which is important for some applications.