Hydrophobic membrane Materials for filter venting applications

#The present invention relates to filtration media having both hydrophobic (water-repellent) properties. The filtration media are produced using a fluorothermoplastic material, such as a terpolymer of tetrafluoroethylene, vinylidene fluoride, and hexafluoropropylene. The invention also relates to methods of preparing such filtration media using casting solution phase inversion.

#Hydrophobic filters are used in filtration of gases, in venting filters, and as gas vents. These hydrophobic filters allow gases and vapors to pass through the filter while liquid water is repelled by the filter.

#Polytetrafluoroethylene (PTFE) has been the most commonly used material in filters for gas venting. PTFE is chemically and biologically inert, has high stability, and is hydrophobic. PTFE filters therefore allow gases to be selectively vented while being impervious to liquid water.

#FIG. 1a provides a SEM image of the skin side of the membrane of Example 1.

#FIG. 1b provides a SEM image of the dull side of the membrane of Example 1.

#FIG. 2a provides a SEM image of the skin side of the membrane of Example 2.

#The following description and examples illustrate a preferred embodiment of the present invention in detail. Those of skill in the art will recognize that there are numerous variations and modifications of this invention that are encompassed by its scope. Accordingly, the description of a preferred embodiment should not be deemed to limit the scope of the present invention.

#The preferred embodiments provide hydrophobic filters that have asymmetric or isotropic structures, high gas permeabilities, and that repel water. The preferred embodiments also include methods of preparing such filters by casting solution phase inversion.

#The filter media are prepared using a fluorothermoplastic, such as a terpolymer of tetrafluoroethylene (TFE), vinylidene fluoride (VDF), and hexafluoropropylene (HFP). The filters have high permeabilities for airflow and reject liquid water, as evidenced by high water penetration pressures. The filters are useful, for example, as air filters or vent filters for intravenous (IV) or other medical devices.