| 摘要 |
A high efficiency particulate air (HEPA) filter made from a layer of electrostatically-charged thermoplastic fiber scrim that is point-bonded to a layer of glass fiber batting to form a composite layer defining an area, wherein the point-bonding is distributed over substantially all of the area of the composite layer and the bond points constitute approximately 1% to approximately 6% of the total surface area of the welded filter material, and wherein the composite layer is substantially uncompressed. Also, a process for forming the filter by providing an ultrasonic rotary drum having a large number of projections from the surface of the drum, passing a layer of electrostatically-charged thermoplastic fiber scrim resting on top of a layer of glass fiber batting over said drum in such a manner that said projections do not substantially penetrate into the subassembly, and passing the subassembly resting on top of the projections under an ultrasonic horn emitting high frequency sound waves into the subassembly to form point-bonds in the vicinity of the projections.
|
