In particles removal with extremely high filtration efficiency and the ability to block submicron airborne particles by a sieving mechanism is provided. This novel nanoporous filter advantageously combines extremely high transmittance for visible light and ultraviolet light, reusability after cleaning or disinfection by ultraviolet irradiation or simple washing, a customizable sieving pore size ranging from a few nanometers to 500 nanometers, and the ability to carry bactericidal, virucidal or other reagents or particles on the nano or micro scale.

The disclosed technology includes an air filter box for filtering particulates from air. The air filter box can include a filter media pack having a filter layer and a plurality of filter media supports configured to support the filter layer. The air filter box can also include a filter housing having an inlet, an outlet, and a plurality of support tabs configured to align and support the filter media pack inside of the filter housing. The filter media pack can be configured to be folded and placed inside of the housing for cooperative engagement with the support tabs. The filter box can be configured to channel a mixture of air and particulates from the inlet, through the filter media pack, and out the outlet to create filtered air.

A shaped cross-section composite fiber for an intake filter is manufactured from a single material of polypropylene, without separate binder processing by using the single material of polypropylene as a filter material. The shaped cross-section composite fiber includes: a sheath comprising a reformed polypropylene resin; and a core comprising a polypropylene resin, where the sheath and the core are combined to provide a sheath-core structure.

A filtration media that may be mounted in a frame and placed in a central heating, cooling and/or ventilation system. The media has symmetrical characteristics such that, when mounted in the frame, the resulting filter may be mounted with either one major surface of the filtration media receiving the air flow or the opposite major surface receiving the air flow. Regardless of how the filter is oriented, the performance of the filter is the same due to the symmetrical characteristics of the filtration media mounted therein.

A mask is provided according to the present application. The mask includes a mask body with filtering performance and a flexible support frame. The support frame is arranged in the mask body and connected to the mask body. The mask body includes a first filter area corresponding to the support frame and a second filter area surrounding the support frame. While the mask is in use, the support frame supports the mask body, so that the first filter area and at least part of the second filter area are spaced apart from the user's face. When the mask according to the present application is worn, the support frame separates the whole first filter area and at least part of the second filter area of the mask body from the wearer's face, which significantly increases the filter area of the mask and makes the wearer's breathing smoother.

An air filter medium includes a collection layer, an air-permeable adhesive layer, and a porous fluorine resin membrane in this order from upstream to downstream of the filter medium. An initial pressure drop of the filter medium at a permeate flow rate of 5.3 cm/sec is 250 Pa or less. When a test is performed in which polydisperse polyalphaolefin particles having a peak in number in a particle size range of 0.1 to 0.2 μm are allowed to pass through the filter medium at a concentration of 0.2 to 0.5 g/m.sup.3 and a linear velocity of 5.3 cm/sec, the holding amount is 43.0 g/m.sup.2 or more from a moment when the holding amount reaches 20 g/m.sup.2 to when a moment the pressure drop reaches PD.sub.1+120 Pa, where PD.sub.1 is the pressure drop of the filter medium at the moment when the holding amount reaches 20 g/m.sup.2.

Filter media having a design embossed into the media are described. In some arrangements, the filter media is pleated filter media. In other arrangements, the filter media includes a plurality of channels, such as tetrahedron channels. The filter media includes a pattern of interrupted straight or angled embossments that help maintain separation between adjacent layers of the filter media. The embossments allow for two adjacent media layers (e.g., mating surfaces of the filter media) to remain separated, thereby increasing dust holding capacity and lowering pressure drop ever similarly configured filter media not having the embossments.

Filter media having a design embossed into the media are described. In some arrangements, the filter media is pleated filter media. In other arrangements, the filter media includes a plurality of channels, such as tetrahedron channels. The filter media includes a pattern of interrupted straight or angled embossments that help maintain separation between adjacent layers of the filter media. The embossments allow for two adjacent media layers (e.g., mating surfaces of the filter media) to remain separated, thereby increasing dust holding capacity and lowering pressure drop over similarly configured filter media not having the embossments.

The electret-treated sheet includes: a core layer (A) which is a porous film containing at least a thermoplastic resin; a surface layer (X) disposed on one side of the core layer (A); and a back surface layer (Y) disposed on the other side of the core layer (A), the surface layer (X) and the back surface layer (Y) each having a charged outermost surface, wherein the electret-treated sheet has a water vapor permeability coefficient of 0.1 to 2.5 g.Math.mm/m.sup.2.Math.24 hr; the core layer (A) has a pore aspect ratio of 5 to 50 and an average pore height of 2.5 to 15 μm; the surface layer (X) and the back surface layer (Y) each have a thickness of 5 to 200 μm; and the surface layer (X) includes a heat seal layer (B) including the outermost surface, wherein the heat seal layer (B) has a melting point of 50 to 140° C.

A replaceable air filter element has a multilayer filter medium panel configured for mounting on a reusable exoskeleton support frame. The exoskeleton support frame is installable on a flow face of the filter medium panel and is provided with U-shaped locking members configured to detachably engage with and mount the filter medium panel. The exoskeleton support frame is configured to be reused such that only the filter medium panel is replaced, thereby reducing the environmental waste and making for a “green” eco-friendly air filter element.