FILTER UNIT

PROBLEM TO BE SOLVED: To provide a filter unit capable of reducing maintenance such as washing cleaning or the like and capable of ensuring good dust separability and air permeability over a long period of time. SOLUTION: A porous film 26 comprising PTFE is provided on the upstream side surface of a base material with respect to suction flow and a perforated protective film 5Bc having a strength higher than that of the porous film 26 is arranged to the upstream side of the porous film 26 in a freely detachable manner to expose the porous film 26 to the outside. By this constitution, by utilzing the good dust separability of the PTFE porous film 26, the dust adhering to the surface of the PTFE porous film 26 can be simply removed by vibration or the like and, when the dust impossible to remove even by vibration or the like begins to deposit, the perforated protective film 5Bc is detached from the PTFE porous membrane 26 to enable a user to perform the washing cleaning of the PTFE. The good dust separability of the filter unit can be held over a long period of time while solving the problem of brittleness possessed by the PTFE porous membrane 26 having good dust separability. COPYRIGHT: (C)2006,JPO&NCIPI