The invention relates to a method for producing a zigzag-folded nonwoven material for a filter, wherein the nonwoven material is produced by a melt-spinning process, comprising the following work steps: folding the nonwoven material by means of a folding device, whereby a plurality of folds results, wherein the folds divide the nonwoven material into first limbs and second limbs such that the nonwoven material is folded in zigzag form; and subsequently welding a weld region of the first limb of a fold to at least one weld region of the second limb of a fold by means of a thermal-contact welding process, wherein a welded joint is formed between the two facing sides of the limbs of a fold. The invention furthermore relates to a corresponding apparatus and a corresponding nonwoven material.

The technology disclosed herein relates to filter assemblies and methods of making filter assemblies. One filter assembly has a first sheet of filter media having a first perimeter region and a second sheet of filter media having a second perimeter region. The first perimeter region and the second perimeter region are bonded in a rim region. A plurality of adsorbent beads are disposed between the first sheet of filter media and the second sheet of filter media, and a substantial portion of the plurality of adsorbent beads are unbonded. Other embodiments are also described.

A filter including a first flow face extending along a lateral direction and a transverse direction of the filter, wherein the first flow face includes at least one contaminant retention layer first edge and at least one flow defining layer first edge, a second flow face spaced in an axial direction from the first flow face, wherein the second flow face extends along the length and the width of the filter and includes at least one contaminant retention layer second edge and at least one flow defining layer second edge, at least one contaminant retention layer extending from the contaminant layer first edge to the contaminant layer second edge, and at least one flow defining layer adjacent to at least one of the contaminant retention layers, the at least one flow defining layer extending from the flow defining layer first edge to the flow defining layer second edge, wherein at least one of the flow defining layers defines at least one fluid flow path in the axial direction as fluid moves from the first flow face toward the second flow face.

An air filter including a filter support that supports porous, polymeric sorbent particles that comprise a divalent metal impregnated therein.

Fiber webs that may be used as filter media are provided. In some embodiments, the filter media may include multiple layers. Each layer may be designed to have separate functions in the filter media. For example, a first layer may be provided for improving dust holding capacity, a second layer for improving efficiency, and a third layer for providing support and strength to the media. By designing the layers to have separate functions, each layer may be optimized to enhance its function without negatively impacting the performance of another layer of the media.

An air filtration device may include a high efficiency particulate air (HEPA) filtration media configured to filter particulates of at least 0.3 microns in diameter. The HEPA filtration media may include graphene oxide (GO) as an antibacterial and antiviral material configured to inactivate trapped micro-organisms. The HEPA filtration media may be a mat of randomly arranged fibers coated with GO or a mat of randomly arranged GO fibers. The device may be shaped and configured for use in an air purification system or for use in a protective face mask.

Self-sterilizing filtration materials are disclosed that include at least one polydopamine-functionalized layer. The at least one polydopamine-functionalized layer is configured to heat to a sterilization temperature when illuminated by light with a light intensity. The self-sterilizing filtration materials may be included in a filtering respirator mask. Methods of sterilizing filtration materials and filtering respirator masks containing at least one polydopamine-functionalized layer by exposing to sunlight are also disclosed. In addition, methods of producing a self-sterilizing filtering respirator mask by polydopamine-functionalizing at least one layer of the filtration material in an existing filtering respirator mask.

An air filter medium includes a first porous PTFE membrane and a second porous PTFE membrane. The air filter medium (10) 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 thickness of the first porous PTFE membrane is in the range of 4 to 40 μm and a specific surface area of the first porous PTFE membrane is 0.5 m.sup.2/g or less.

A filtration media with improved filtration, strength, tear resistance and air permeability in the form of a relatively thin and lightweight wet-laid fibrous web that has a wet Mullen ratio of 60% to 80% to ensure that the media is flexible enough to be formed into a fluted structure, and strong enough to retain the fluted structure when wound into a roll and to permit further processing without the media becoming too brittle. The filtration media comprises a blend of cellulose and synthetic fibers having a weight percent of 81 wt % to 87 wt % of a weight of the media and a resin binder having a weight of 13 wt % to 19 wt % (preferably about 16 wt %) of the weight of the media.

Disclosed is a particulate matter (PM) capturing and collecting filter device having a target-coated liquid film. More specifically, disclosed is a PM particle capturing and collecting filter device having a target-coated liquid film in which a spreading phenomenon in which a liquid material spreads outside the filter is suppressed. Disclosed is a filter device for capturing and collecting PM particles, in which a liquid film having interface energy control and capillary force induction is used for effective PM particle capturing and collecting, and a surrounding portion is formed for preventing spreading of a liquid material on a substrate.