| 摘要 |
A dust sock filter medium laminate is provided which has at least two nonwoven webs of microfibers which have an average diameter (using a sample size of at least 10) between about 10 and 25 microns and which webs have been joined by a method comprising the steps of (a) directing the component layers to a separation zone, (b) applying water in the amount of from about 5% to 25% based on the weight of the combined layers, (c) combining the component layers, (d) passing the combination through a sonic bonder operating within the range of up to about 40,000 cps against a patterned anvil to produce a corresponding pattern of thermal bond areas over about 3% to 25% of the surface area of the combination, and, (e) drying the sonically bonded combination.
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