Trichlorofluoromethane, boiling

For the preparation of higher-boiling fluorides, lower-boiling solvents, such as pentane, di-chloromethane, or trichlorofluoromethane, are useful. 

Foams may be prepared by either one of two fundamental methods. In one method, a gas such as air or nitrogen is dispersed in a continuous liquid phase (e.g. an aqueous latex) to yield a colloidal system with the gas as the dispersed phase. In the second method, the gas is generated within the liquid phase and appears as separate bubbles dispersed in the liquid phase. The gas can be the result of a specific gasgenerating reaction such as the formation of carbon dioxide when isocyanate reacts with water in the formation of water-blown flexible or rigid urethane foams. Gas can also be generated by volatilization of a low-boiling solvent (e.g. trichlorofluoromethane, F-11, or methylene chloride) in the dispersed phase when an exothermic reaction takes places, (e.g. the formation of F-11 or methylene chloride-blown foams). 

The main CFC to be replaced is CFC Rll (trichlorofluoromethane), which offers high molecular weight and therefore low thermal conductivity, low boiling point and therefore good blowing action, high chemical stability, non-toxicity, non-flammability, and low price. 

The water-isocyanate reaction forming carbon dioxide is commonly used to form open-cell flexible foams. Trichlorofluoromethane (TCFM) is a physical blowing agent relying on heat from the urethane reaction exotherm to boil this is used to form rigid closed-cell foams and most self-skinned moulded products. There is considerable concern over the effect of fluorocarbons on the Earth s ozone layer, and suitable replacements are actively being sought. 

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