A filter cartridge is provided that includes a plurality of individual fibers, wherein the individual fibers have different cross sections and are arranged into a random lattice of fibers. The filter cartridge also includes at least one flat sheet media, wherein the plurality of individual fibers are thermally bound to the at least one flat sheet media, wherein the flat sheet media is spirally wound to create a cylindrical profile.

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.

An air filter medium includes a first porous PTFE membrane and a second porous PTFE membrane. The air filter medium has a first main surface and a second main surface, and the first porous PTFE membrane and the second porous PTFE membrane are arranged so that an air flow moving from the first main surface to the second main surface passes through the first porous PTFE membrane and subsequently through the second porous PTFE membrane. A contact angle of the first porous PTFE membrane with water is in the range of 154° to 165°.

The invention relates to a method of producing a multilayer filter medium, comprising at least the production steps listed below: providing a woven fabric layer (12) having passage points (24) for fluid; providing a nonwoven layer consisting of a spunbonded nonwoven (18) and having additional passage points (28) for fluid; and joining the two superimposed layers (12, 18) along contact points (30) by melting the nonwoven layer (18) in such a way that while the additional passage points (28) enlarge, the molten spunbonded nonwoven material flows at least in part to the contact points (30) and then cumulatively curs there to produce firm connection points between the two layers (12,18).

The filter medium for a filter of the present invention has a laminate structure in which a long-fiber non-woven fabric and a wet non-woven fabric are stacked, wherein the wet non-woven fabric comprises vinylon, polyester, and polyvinyl alcohol, is disposed on a most upstream side of air flow, has a surface located on the most upstream side of air flow, the surface having a surface roughness (SMD) not larger than 2.7 μm, and has a surface stacked on the long-fiber non-woven fabric, the surface having (a) a surface roughness (SMD) not smaller than 3.0 μm or (b) a rough texture (MMD) not lower than 0.02.

A particle filtration system that includes first, second and third filter segments that each include several first, second and third filters. Each first, second and third filter includes a fibrous layer sandwiched between a pair of surface or outer layers. The range of pore sizes of each first, second and third filter varies according to the density of the surface layers relative to the fibrous layers.

A nanofiber based multi-layer filtration material suitable for use in providing air filtration to a user's respiratory system may be provided. as an air filtration garment and/or other air filterina devices such as a face mask, mask and garments or the like. The laminate includes a one or more fabric layer adjacent to one or more nanofiber layers.

Non-woven fiber webs and articles (e.g., filter media) comprising non-woven fiber webs are generally described. In some embodiments, a non-woven fiber web described herein formed via certain non-wetlaid processes may exhibit enhanced physical properties. For example, a non-woven fiber web may be subjected to a carding (e.g., cross-lapped carding) process. In some cases, the non-woven fiber webs described herein may be calendered to further enhance their physical properties.

A protective fabric which includes at least one structural layer and a ceramic composite material layer fixed to the at least one structural layer, is provided. The structural layer can include a non-woven material made from or containing synthetic fibers. The ceramic composite material layer is formed of ceramic composite material powder which includes a ceramic carrier, and iron-silver crystals containing zero-valent iron and zero-valent silver supported on the ceramic carrier. The protective fabric is effective for removing VOCs, suppressing bacterial growth, and filtering or inactivating virus, such as SARS-CoV-2 virus. Protective products or articles incorporating the protective fabric are also provided.

The present disclosure provides a filter material used for automobile air conditioning and capable of filtering out volatile organic compound (VOC) gas, including a sandwich structure (100) and an activated carbon fiber (ACF) non-woven fabric layer (200) located at one side of the sandwich structure (100), where, the ACF non-woven fabric layer (200) is composed of interleaved ACFs, and the ACF non-woven fabric layer (200) is compounded with the sandwich structure (100) via hot melt adhesive (HMA) (210).