Air filter

摘要

The object of the present invention is to provide an air filter where the lifetime of the air filter is long and a carbon dust can be efficiently caught with keeping the cost low. The air filter of the present invention comprises a first filter layer 11 impregnated with oil; an oil repellent layer 11a disposed in the downstream side of the first filter layer 11, having the property of repelling the oil; and a second filter layer 12 disposed in the downstream side of the oil repellent layer 11a, impregnated with no oil. The transfer of the oil to the second filter layer 12 is controlled by the oil repellent layer 11a.