| 摘要 |
PURPOSE:To prevent not only water, which had penetrated into a nonwoven fabric layer to a certain degree, from penetrating into an air outflow side but also dust from being involved in the air outflow side, by applying water repelling processing at least to the air inflow side of the nonwoven fabric layer. CONSTITUTION:Water repelling processing is applied to the whole of a density gradient type filter material. By this processing, even if water is penetrated into an air cleaner 1 from an inlet 3 and adhered to a filter body 8, the addition amount of a water repellent in an air inflow side of the filter material 8c of the filter body 8 is little and the density of the water repellent in the air outflow side thereof is high and, therefore, water is not penetrated into the air outflow side though penetrated into the filter body 8 to a certain degree and transmitted through the filter body 8 to be flowed down on a dust pan 13. Because the air inflow side of the filter body 8 is always cleaned by the water, the cleaning period of the filter body 8 can be extended.
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