| 摘要 |
PROBLEM TO BE SOLVED: To obtain an air filter for coarse dust at a low cost which causes no environmental problems even when it is incinerated, by using a filament nonwoven fabric of a specified unit weight comprising a thermoplastic core- sheath conjugate fiber having a specified fiber diameter and by forming the filter to have specified characteristics such as initial pressure loss and dust retaining amt. SOLUTION: In the production of a unit-type air filter for coarse dust to be attached to an intake port of a room air conditioner and the like, a filament nonwoven fabric having 30 to 80g/m<2> unit weight is used. This nonwoven fabric consists of a thermoplastic core-sheath conjugate fiber having 25 to 50μm fiber diameter and is formed to have 1.0 to 3.0mm thickness in order to obtain a certain filtering area and shape holding property after the fabric is pleated. To increase the filtering area, the fabric is embossed by heat to form large recesses. In order to obtain the embossing effect, the fabric is preferably formed to have >=0.5mm thickness. Thereby, the obtd. air filter for coarse dust have such performance as the third or higher grade of wear resistance, <=80Pa initial pressure drop and >=15g/m<2> dust holding amt.
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