Ultrasonically bonded electret filter media

Abstract

Filter media and filters are provided having a fibrous web including first and second dissimilar electret fibers ultrasonically bonded to each other. The first and second electret fibers may be directly bonded to each other without needle punching, which substantially maintains the thickness or loft of the fibrous web of the filter media and filters. Maintaining the thickness or loft of the fibrous web during the bonding process decreases the pressure drop across the filter media and increases its dust holding capacity. Medical grade filters and/or self-supporting (i.e., self-pleatable) air filters are also provided. The medical grade filters and/or self-supporting air filters may include one or more support layers ultrasonically bonded to the fibrous web or fiber layers without needle punching, which maintains the stiffness of the support layers and allows the filter to be produced in a single manufacturing step.

Dependencies are inferred from the claim text.