Patent ID: 7922959

Claim:
A method of making a composite filter media structure comprising: forming a nonwoven fabric mat comprising a plurality of synthetic fibers by a spunbond process; calendering the nonwoven fabric mat with embossing calender rolls to form a bond area pattern comprising a plurality of substantially parallel discontinuous lines of bond area to bond the synthetic fibers together to form a nonwoven fabric, the nonwoven fabric having a filtration efficiency of about 35% to less than 50%, measured in accordance with EN 1822 (1998) test procedure; and applying a nanofiber layer by electro-blown spinning a polymer solution to form a plurality of nanofibers on at least one side of the nonwoven fabric to form the composite filter media, the composite filter media having a minimum filtration efficiency of about 70%, measured in accordance with EN 1822 (1998) test procedure.