Patent ID: 8608817

Claim:
A filter medium, comprising: a first layer; a second layer comprising a meltblown material; and an adhesive material between the first and second layers, wherein the adhesive layer is constructed and arranged to adhere the first layer to the second layer and to permit fluid to pass through the adhesive layer, wherein the filter medium has: an initial dust capture efficiency of at least 80% and a dust holding capacity of at least 50 g/m 2 , wherein the initial dust capture efficiency and the dust holding capacity are measured by taking a 100 cm 2 surface area of the filter medium and challenging the medium with a fine dust (0.1-80 μm) at a concentration of 200 mg/m 3 and a face velocity of 20 cm/s, wherein the initial dust capture efficiency is measured after one minute and the dust holding capacity is measured when the pressure reaches 1800 Pa; and an initial cleanability test time and an aged cleanability test time, the aged cleanability test time being at least 70% of the initial cleanability test time, wherein the initial cleanability test time is the amount of time it takes to complete 30 test cycles and the aged cleanability test time is the amount of time it takes to complete 30 test cycles after aging the filter medium, wherein each test cycle comprises sending AC fine dust at 16 g/hr through the filter medium at a test area of 177 cm 2 , a face velocity of 5 cm/s, and when the filter medium reaches a pressure of 10 mBar subjecting the filter medium to a 150 millisecond pulse at 4 bar to remove AC fine dust from the filter medium, wherein aging comprises continuously exposing the filter medium to AC fine dust at 12 g/hr for 10,000 aging cycles and subjecting the filter medium to a 150 millisecond pulse at 4 bar 14 times per minute, wherein the aging cycles are defined between consecutive pulses.