There is provided a liquid filter having a small pressure loss and a manufacturing method for a liquid filter. The liquid filter is a liquid filter that is composed of a nonwoven fabric formed of fibers containing a water-insoluble polymer and a hydrophilizing agent. In the nonwoven fabric, a fiber density continuously changes in a film thickness direction, a fiber density difference is present in the film thickness direction, the fiber density of one surface of the nonwoven fabric in the film thickness direction is maximal, and the fiber density of the other surface of the nonwoven fabric in the film thickness direction is minimal.

There are provide a cell separation filter with which cells can be separated without damage and can suppress adsorption, a filtering device, and a manufacturing method for a cell separation filter. The cell separation filter is composed of a nonwoven fabric that is formed of fibers containing a water-insoluble polymer and a hydrophilizing agent and has a fiber density difference in the film thickness direction. The nonwoven fabric has an average through-hole diameter of 2.0 μm or more and less than 10.0 μm, a void ratio of 75% or more and 98% or less, a film thickness of 100 μm or more, and a critical wet surface tension of 72 mN/m or more.

Filter media comprising adsorptive particles are generally described. In some embodiments, the adsorptive particles are present in a relatively large amount, in a layer discrete from one or more other layers and/or fiber webs also present in the filter media, and/or in a layer that comprises a relatively low amount of fibers. In some embodiments, the filter media further comprises a non-woven fiber web comprising fibers with relatively small diameters.

Filter media, including those suitable for hydraulic, fuel, HVAC, HEPA, and/or other applications, and related methods are provided. In some embodiments, a filter media described herein may include a layer (e.g., a fine fiber layer) comprising a plurality of fibers comprising polyamide 11. In some embodiments, a filter media comprises a layer (e.g., a fine fiber layer) comprising a plurality of electrospun fibers comprising a material having one or more advantageous properties. In an exemplary set of embodiments, the plurality of fibers comprise polyamide 11 (e.g., Nylon 11). In some embodiments, the polyamide 11 fibers are produced by an electrospinning process.

Articles and methods involving filter media are generally provided. In certain embodiments, the filter media includes at least a first layer, a second layer, and an adhesive resin positioned between the first layer and the second layer. In some embodiments, the first layer may be a pre-filter layer or a support layer. The second layer may, for example, comprise fibers formed by a solution spinning process and/or may comprise fine fibers. In some embodiments, the adhesive resin may be present in a relatively low amount and/or may have a low glass transition temperature. The filter media as a whole may have one or more advantageous properties, including one or more of a high stiffness, a high bond strength between the first layer and the second layer, a high gamma, and/or a low increase in air resistance after being subjected to an IPA vapor discharge. The filter media may be, for example, a HEPA filter and/or an ULPA filter.

Filter media comprising non-woven fiber webs having one or more advantageous physical properties are generally described. In some embodiments, a filter media and/or non-woven fiber web described herein comprises a combination of fibers that results in enhanced physical properties. For example, the non-woven fiber web may comprise a combination of fiber types that is advantageous, such as a combination comprising fibrillated fibers, glass fibers, and/or binder fibers. In some cases, the filter media and/or non-woven fiber web comprising the combination of fibers may be formed into undulations (e.g., by a creping and/or microcreping process) to further enhance the physical properties of the filter media and/or non-woven fiber.

Filter media comprising non-woven fiber webs having one or more advantageous physical properties are generally described. In some embodiments, a filter media and/or non-woven fiber web described herein comprises a combination of fibers that results in enhanced physical properties. For example, the non-woven fiber web may comprise a combination of fiber types that is advantageous, such as a combination comprising fibrillated fibers, glass fibers, and/or binder fibers. In some cases, the filter media and/or non-woven fiber web comprising the combination of fibers may be formed into undulations (e.g., by a creping and/or microcreping process) to further enhance the physical properties of the filter media and/or non-woven fiber.

Filter media comprising non-woven fiber webs and having one or more advantageous structural properties are generally described. In some embodiments, a filter media and/or non-woven fiber web described herein has one or more properties that are both beneficial and easily obtainable by undulating the non-woven fiber web, such as by performing a creping procedure. This property may be characteristic of the procedure employed to form the undulations (e.g., creping and/or microcreping), or may be attainable via one or more methods of undulation.

Provided are: a filter medium with high dust collection efficiency, low pressure loss, and a long lifespan; and a filter material used for the filter medium. This composite structure includes ultrafine fibers having a fiber diameter of less than 500 nm, and beads. The outermost surface of the composite structure has at least 500/mm.sup.2 of beads with a diameter of 5 μm or more. The ultrafine fibers and the beads preferably have the same component.

Provided are an air filter medium and an air filter product that can have a long life. The air filter medium includes a filter medium layer that includes first fibers having an average fiber diameter of not less than 5 μm and not greater than 50 μm and second fibers disposed in gaps between the first fibers and having an average fiber diameter of not less than 30 nm and not greater than 1 μm.