Abstract: A membrane support material is support material for adhering a membrane to a membrane attachment surface. A plurality of non-woven fiber sheets, which are three-dimensional fiber aggregates, are layered together and thermal and pressure processed to bond fibers of the non-woven fiber sheets and form a single sheet of support material. Each layer of non-woven fiber sheet has a different longitudinal-to-lateral tensile strength ratio (k), which is the ratio (f2/f1) of the tensile strength in the lengthwise direction (f2) to the tensile strength in the width direction (f1), and in the thermal and pressure processed state, the support material membrane attachment surface has curvature in the lateral (width) direction with an outward protruding (convex) center region.

Abstract: The membrane support material is support material for adhering a membrane to a membrane attachment surface. A plurality of non-woven fiber sheets, which are three-dimensional fiber aggregates, are layered together and thermal and pressure processed to bond fibers of the non-woven fiber sheets and form a single sheet of support material. Each layer of non-woven fiber sheet 1 has a different longitudinal-to-lateral tensile strength ratio (k), which is the ratio (f2/f1) of the tensile strength in the lengthwise direction (f2) to the tensile strength in the width direction (f1), and in the thermal and pressure processed state, the support material membrane attachment surface has curvature in the lateral (width) direction with an outward protruding (convex) center region.

Abstract: 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.