ELASTOMER TREATMENT PROCESS TO DECREASE PEROXIDE LEVELS

摘要

A novel process has been developed for the treatment of cross-linked ethylen e- propylene diene monomer (EPDM) elastomer material to decrease its residual peroxide levels. EPDM is used to form the seats and neck gaskets of metering valves used in metered-dose inhalers (MDI). For filled and inverted MDI units these EPDM components are in direct contact with the pharmaceutical formulation media. The process involves exposing the EPDM valve components to a solution of 2-mercaptoethanol, a chemical reducing agent. The 2-mercaptoethanol greatly diminishes the residual peroxide levels in EPDM by reducing the peroxide functional groups to the corresponding hydroxyl groups. EPDM components treated in this manner have demonstrated ve ry low peroxide levels and, consequently, greatly improved compatibility with the pharmaceutical formulation in the inhaler. An advanta ge of this approach is that the treated EPDM would likely retain its favorable physical properties and its good performance in meterin g valves. In this work 2-mercaptoethanol was used as the model reducing agent. It is believed, however, that similar positive results can b e obtained using other reducing agents, notably other volatile compounds containing sulfur in one of its lower valence states (i.e. other thiol compounds or sulfur dioxide).