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.

This disclosure describes a filtration composite that includes multiple layers of filtration media. In some embodiment, the filtration composite is preferably substantially glass-free or glass-free. When the composite is glass-free or substantially glass-free, the composite preferably exhibits capacity and efficiency comparable to or better than similar glass-containing filtration media. The composite includes a first nonwoven filtration medium including bicomponent fibers, efficiency fibers having a fiber diameter in a range of 1 micron to 5 microns, and microfibrillated fiber; an optional second nonwoven filtration medium; and a third nonwoven filtration medium including efficiency fibers having a fiber diameter of at least 0.1 micron and less than 1 micron.

A spunbond non-woven fabric includes a nonbonded projected part and a bonded recessed part. Bending resistance in a machine direction of the spunbond non-woven fabric is 20 mN or more and 40 mN or less, and in a non-woven fabric cross-section, a thickness from one surface to another surface of the projected part is determined to be t.sub.A, a thickness from one surface to another surface of the recessed part is determined to be t.sub.B, and respective distances from one surface of the projected part to one surface of the recessed part are determined to be t.sub.C and to (t.sub.C<t.sub.D), and the spunbond non-woven fabric has a relation represented by formulas (1) and (2) below:

0.5≤1−t.sub.B/t.sub.A<1.0  (1)

0.35<t.sub.C/t.sub.D<0.65  (2).

Filter media are described. In particular, a filter media includes an intake side, an exhaust side, and a plurality of fibers distributed throughout the filter media. The fibers have a plurality of deniers, and fibers disposed proximate the intake side have a first denier and fibers disposed proximate the exhaust side have a second denier. The first denier is larger than the second denier.

This disclosure describes a filtration medium that is preferably glass-free or substantially glass-free. In some embodiments, the filtration medium preferably exhibits capacity and efficiency comparable to or better than similar glass-containing filtration media. The filtration medium includes bicomponent fibers, efficiency fibers (for example, PET fibers), and microfibrillated fibers. The efficiency fibers include fibers having a fiber diameter in a range of 1 micron to 5 microns and fibers having a fiber diameter of at least 0.1 micron and less than 1 micron.

A composite fiber having a core sheath-structure that includes a core portion having an electrically conductive material, and a sheath portion having a ceramic component covering the core portion. The composite fiber is constructed such that, when the core portion is connected to a ground, the sheath portion exhibits one of a positive surface potential or a negative surface potential over an entire surface of the sheath portion.

A filter medium is disclosed having a nonwoven layer, which has bicomponent fibres, and a melt-blown layer, which comprises polyester fibres having an average diameter (d1) of less than 1.8 μm. The thickness of the nonwoven layer is less than 0.4 mm at a contact pressure of 0.1 bar. At least 25% of the polyester fibres of the melt-blown layer have a diameter (d) of less than 1 μm.

This disclosure describes a filter medium that minimizes the adverse effects of variations in flow rate on filter medium efficiency without a corresponding increase in pressure drop. The filter medium includes a support layer, a continuous fine fiber layer, and an efficiency layer. The continuous fine fiber layer includes a continuous fine fiber that has a diameter of up to 10 micrometers and is located downstream of the efficiency layer.

A thermoplastic core-sheath fiber comprises: a polymer fiber core having a coextensive sheath layer disposed thereon, and an electrostatic charge enhancing additive. The sheath layer may comprise poly(4-methyl-1-pentene) and the fiber core and the sheath layer have different compositions. At least one of the fiber core or the sheath layer comprises an electret charge. A nonwoven fibrous web comprising the core-sheath fibers and a respirator including the nonwoven fibrous web are also disclosed.

Thermoplastic bicomponent binder fiber can be combined with other media, fibers and other filtration components to form a thermally bonded filtration media. The filtration media can be used in filter units, such as breather caps. Such filter units can be placed in the stream of a mobile fluid and can remove a particulate and/or fluid mist load from the mobile stream. The unique combination of media fiber, bicomponent binder fiber and other filtration additives and components provide a filtration media having unique properties in filtration applications.