| 摘要 |
PROBLEM TO BE SOLVED: To suppress reduction of carbon efficiency at high flow speed of a filtering medium 2 combined with a wet layer 5 and a dry layer 6. SOLUTION: The filtering medium 2 has a two layer structure of the wet layer 5 in an upstream side and the dry layer 6 in a downstream side. Any of the wet layer 5 and the dry layer 6 comprises a filter paper and two sheets of paper layers paper-made respectively are joined to one sheet of paper by a paper-making/joining method. A surface of the dry layer 6 is coated with a phenol resin dissolved with a fluorine resin, i.e., an oil repellant and a surface of the wet layer 5 is coated with a phenol resin containing no fluorine resin. After performing pleat-folding processing, an oil such as viscous oil is sprayed onto the wet layer 5 side. A pore size of the second filter paper 6A becoming the dry layer 6 is smaller than that of the first filter paper 5A becoming the wet layer 5. Thereby, capturing efficiency at a high flow speed of a carbon particle mainly captured by the dry layer is enhanced. COPYRIGHT: (C)2005,JPO&NCIPI
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