ZEPHEX®134a and ZEPHEX®227ea are low boiling, non-toxic and non-flammable hydrofluoroalkane (HFA) aerosol propellant gases. Both easily comply with the relevant industry toxicological specifications (IPACTl and ll).
Whilst chemically quite similar, there are sufficient differences to give them physical properties that are complementary. If a formulation chemist has access to both, most MDI formulation challenges should be surmountable by choosing the appropriate HFA or blend thereof.
Generally the chemist should first attempt to achieve a successful formulation using ZEPHEX®134a alone. If this proves not to be possible the chemist should then consider using the higher priced ZEPHEX®227ea either alone or in blend.
The key differing properties of the two propellants are summarised below.
|Property||ZEPHEX® 134a||ZEPHEX® 227ea||Comments|
|Density(Kg/m³ at 25°C)||1206.8||1387||Adjustment of liquid density valuable as a means of stabilising suspensions. Attempt to approach density of suspended solids. Use blending for fine tuning.|
|‘Solvency’||‘Polar’ Alcohol−like||‘Less polar’. More CFC-like||Description of the relative solvencies of these two HFAs, and how they can be further tuned, is complex. More information given in customer zone.|
|Boiling Point (°C)||-26.07||-16.45||Atomising power can be tuned by variation of the boiling point.|
Basic information on both HFAs can be found in the Physical Properties section. More specialised information can be found in the Customer Zone, covering a wide range of topics including compatibilities, properties of mixtures and detailed solvent/non solvent discussion.