| abstract |
A filter including a filter medium with a pleated structure. The medium includes a nanoweb layer and a scrim, wherein the nanoweb layer contains fibers with a number average diameter less than 1 micron and layer thickness less than 50 microns. The ratio of total medium thickness-to-pleat spacing is less than 0.15 and the nanoweb layer has a basis weight of more than about 0.6 gsm. The nonwoven scrim can be a spunbond web, a dry-laid web, a wet-laid web, a cellulose fiber web, a melt blown web and a glass fiber web. |