| 摘要 |
Fluid filtration articles, including composite nonwoven fibrous webs, and methods of making and using such articles as gas or liquid filtration elements. The articles include a population of coarse microfibers having a population median diameter of at least 1 micrometer (mum) formed as a first layer, and a population of fine fibers having a population median diameter less than 10 mum formed as a second layer adjoining the first layer. At least one of the fiber populations may be oriented. In one implementation, the coarse microfibers and fine fibers are polymeric, the coarse microfibers have a population median diameter of at least 10 mum, and the fine fibers have a population median diameter less than 10 mum. In another implementation, the population of fine fibers has a population median diameter less than 1 mum. Optionally, one or both of the first and second layers may include particulates.
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