Patent ID: 8679216

Claim:
A filter element for separating particulate matter from a gas stream comprising a filter medium comprising a porous substrate having two major surfaces wherein the substrate is adhesively bonded over one of the major surfaces to a first nanoweb having a basis weight less than about 2 gsm by a layer of adhesive and wherein the filter medium is made by a process comprising the steps of (a) forming a nanoweb directly onto a carrier layer; (b) providing a porous substrate having two major surfaces; (c) applying a layer of adhesive to at least a portion of one surface of the porous substrate while it is not in contact with the nanoweb; (d) contacting the adhesive layer with the nanoweb and bonding the nanoweb to the porous substrate wherein the adhesive layer securely attaches the nanoweb to the substrate; and (e) optionally removing the carrier layer, thus forming the filter medium; and wherein the substrate and the first nanoweb remain bonded after the filter element has been subjected to a complete test according to VDI 3926.