A method of bonding a nanofiber web of nanofibers having diameters of between about 50 nanometers and about 2,000 nanometers onto a surface of a woven or nonwoven polymeric media having media fiber diameters of between about 700 nanometers and about 50,000 nanometers utilizes exposing the topmost layer of nanofibers and media fibers to a jet of heated air for a time and at a distance such that substantially only the topmost layer of fibers are bonded. The jet of heated air exits through a nozzle slot having a length of less than about 2 inches in the nanofiber web travel direction. The temperature of the heated air ranges from about 2 to about 10 times the nanofiber melting temperature, and heat air has a nozzle slot velocity of greater than about 500 feet/minute. An adhesive may bond the nanofibers, to a media, which may be bi-component fiber fibers.

Provided is a nanofiber sheet that has a high mechanical strength, is excellent in durability, and has a high specific surface area. The nanofiber sheet includes: a plurality of nanofibers; and a bulk portion produced by bonding of the nanofibers, in which 710.sup.3 portion/m.sup.2 or more of the bulk portion satisfying the following formula is contained:
0.5X.sup.2Y5 m.sup.2(1)
where X represents a diameter (m) of each of the nanofibers and Y represents an area (m.sup.2) of an inscribed circle of the bulk portion when viewed from a surface.

Damage is not caused even when oil mist in a gas is trapped, and clogging of a filter paper due to an oil film can be less likely to occur. A filtration member formed by folding a filter paper for trapping oil mist in a gas into a corrugated shape in which mountain folds and valley folds are alternately repeated is provided. The filter paper includes a nanofiber layer formed of polyolefin fibers. In the nanofiber layer, a content of fibers having a fiber diameter of 0.2 ?m to 0.4 ?m is 3% or more, a content of fibers having a fiber diameter of 0.4 ?m to 0.6 ?m is 24% or more, a content of fibers having a fiber diameter of 0.6 ?m to 0.8 ?m is 15% or more, and a content of fibers having a fiber diameter of 0.8 ?m to 1.0 ?m is 9% or more.

A filter includes an electrode; a base layer coupled with the electrode; and a nanofiber layer spun on one side of the base layer and coupled, in which the coupling between the nanofiber layer and the base layer is performed as the nanofiber layer is adsorbed on the base layer by an electric field generated by supplying power to the electrode.

There is provided a nanofibrous filter comprising a substrate and self-assembled nanofibers deposited on the substrate. The self-assembled nanofibers comprise -conjugated molecules self-assembled by non-covalent interactions, wherein the -conjugated molecules are phthalocyanine derivative molecules or diketopyrrolopyrrole derivative molecules. There is also provided a method of preparing the nanofibrous filter.

Filter media are described. The filter media may include multiple layers. In some embodiments, the filter media include a nanofiber layer adhered to another layer. In some embodiments, the layer to which the nanofiber layer is adhered is formed of multiple fiber types (e.g., fibers that give rise to structures having different air permeabilities and/or pressure drops). In some embodiments, the nanofiber layer is adhered to a single-phase or a multi-phase layer. In some embodiments, the nanofiber layer is manufactured from a meltblown process. The filter media may be designed to have advantageous properties including, in some cases, a high dust particle capture efficiency and/or a high dust holding capacity.

A filtration barrier comprises at least one barrier layer which includes polymeric nanofibers interlaced with microfibers, and at least one substrate layer which includes polymeric microfibers. The filtration barrier can be made by electrospinning process.

Provided is a nanofiber vent device for a urea water tank including a filter unit for discharging gas generated in the tank main body and preventing external dust, foreign matter, and moisture from flowing into the tank main body, as a vent device that is installed in a tank main body storing urea water and discharging gas inside the tank main body to the outside.

A filtration barrier comprises at least one barrier layer which includes polymeric nanofibers interlaced with microfibers, and at least one substrate layer which includes polymeric microfibers. The filtration barrier can be made by electrospinning process.

A filtration device including a contoured support having 1) an interior surface, 2) an outside peripheral surface spaced farther from a center of the contoured support than the interior surface, and 3) a rim enclosed and sealed to a perimeter of the contoured support. The filtration device includes macroscopic openings in the contoured support extending from the interior surface to the outside peripheral surface, and a plurality of nanofibers having diameters less than 1 micron. The nanofibers are disposed on the outside peripheral surface of the contoured support, and cover the macroscopic openings to form a filtration medium on the contoured support.