Blowing agents

One of the primary steps in producing polyurethane foams is gas generation. Although the gas phase may be negligible in weight, it is significant in volume and plays a crucial role in the foam’s properties. Gas can be produced in polyurethane foam production through two main methods: chemical and physical, or a combination of both (simultaneous use of physical and chemical agents). Physical blowing agents are low-boiling liquids that do not react with isocyanate groups; they evaporate due to the exothermic reaction heat (generated during the foaming process), producing gas. These include CFCs (chlorofluorocarbons), HCFCs (hydrochlorofluorocarbons), HFCs (hydrofluorocarbons), etc. Chemical blowing agents react with isocyanate groups, producing carbon dioxide gas, including boric acid, water, etc.