Methylal is one of a family of blowing agents that can be used as an alternative HFCs, HCFCs and HFOs. They are particularly suitable for rigid foam applications, but more recently have been used in a continuous flexible block foam plant. This opens up their potential usage considerably.
Many people are concerned that, like pentane, methylal is a highly flammable substance, and companies worry about the cost of transitions from non-flammable HCFCs and HFCs to non-halogenated blowing agents.
Our work shows the flammability of methylal can be significantly reduced by the presence of silicone surfactants. This development could have significant implications for the flammability of polyurethane formulations.
Methylal, or dimethoxymethane, is an easy-to-handle liquid at room temperature, with a boiling point of 42.3°C. There is no requirement to label containers in terms of toxicology – the OEL is 1000ppm – eco-toxicology or atmospheric chemistry according to UNECE GHS/CLP classifications. The ozone depletion potential of methylal is zero, and its global warming potential is much lower than CO2. It is petrochemically derived but, potentially, could be made from bio-methanol.
Methlylal is used in rigid and spray foams, flexible slabstock and moulded foams, integral skin foams, shoe soles and one-component foams. It can be used alone, with water, or in combination with other blowing agents such as HFOs, HFCs and pentanes.CHART HERE