Patent ID: 8512432

Claim:
A composite filter media structure comprising: a base substrate comprising a nonwoven synthetic fabric formed from a plurality of fibers with a spunbond process, said base substrate having a filtration efficiency of about 35% to less than 50% capture of particles having a size of 0.3 μm, measured in accordance with EN 1822 (1998) test procedure, wherein said nonwoven synthetic fabric is comprised of a dual layer containing both round and trilobal fiber cross-sections; and a nanofiber layer deposited on one side of said base substrate, said composite filter media structure having a minimum filtration efficiency of about 70% capture of particles having a size of 0.4 μm, said efficiencies of base substrate and composite media being measured in accordance with EN 1822 (1998) test procedure on a flat substrate at a face air velocity of 5.3 cm/second and wherein said base substrate has a resistance less than about 2.5 mm of water, measured in accordance with EN-1822 (1998), and said composite filter media structure has a resistance less than about 4.0 mm of water, measured in accordance with EN-1822 (1998).