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.

Articles and methods relating to filter media are generally provided. In some embodiments, a filter media has an irregular surface structure. For instance, the filter media may comprise a plurality of peaks that are irregular in one or more ways. A ratio of a peak height standard deviation to an average peak height may be greater than or equal to 0.05, and/or a ratio of a peak spacing standard deviation to an average peak spacing may be greater than or equal to 0.08. In some embodiments, a filter media comprises a non-woven fiber web having a layer thickness of greater than 0.3 mm and/or a stiffness of less than or equal to 100 mg.

Embodiments disclosed herein relate to a pleated filter element having filter media having a downstream layer of filter material and an upstream layer of fibers. A spacing structure defines a void space between the upstream layer of fibers and the downstream layer of filter material.

An air filter medium includes a porous fluorine resin membrane, and further includes, a collection layer, an air-permeable adhesive layer, and an air-permeable supporting layer. The collection layer, the air-permeable adhesive layer, the air-permeable supporting layer, and the porous fluorine resin membrane are placed in this order from upstream to downstream of the air filter medium configured to allow an air flow to pass through the air filter medium. The collection layer is formed of a fibrous material having an average fiber diameter of 5 .Math.m or less. The air-permeable adhesive layer has a grammage of 5.5 g/m.sup.2 or more. The air-permeable supporting layer is formed of a fibrous material having an average fiber diameter of more than 5 .Math.m. This air filter medium is suitable for reducing a pressure drop increase even in an environment including liquid particles such as oil mist.

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.

The present disclosure provides filters that can be removed from surfaces without damage by having reduced or eliminated contribution of a core backing to peel force generated by the adhesive during removal. In some instances, this can be accomplished by a core that loses structural integrity in a direction normal to a plane defined by a major surface. In other instances, the contribution is reduced by compromising the interface between the core and a peelable adhesive layer.

Articles and methods relating to filter media are generally provided. In some embodiments, a filter media has an irregular surface structure. For instance, the filter media may comprise a plurality of peaks that are irregular in one or more ways. A ratio of a peak height standard deviation to an average peak height may be greater than or equal to 0.05, and/or a ratio of a peak spacing standard deviation to an average peak spacing may be greater than or equal to 0.08. In some embodiments, a filter media comprises a non-woven fiber web having a layer thickness of greater than 0.3 mm and/or a stiffness of less than or equal to 100 mg.

Fibrous filter medium that includes a melt-blown filter layer comprising melt-blown fibers and a high-efficiency glass-containing filter layer comprising glass fibers.

A melt-blown nonwoven fabric includes polybutylene terephthalate, in which an intrinsic viscosity of the melt-blown nonwoven fabric is 0.45 dl/g or more and 0.60 dl/g or less.

An array of discrete nanofiber films that are physically separated from one another are described. Techniques for forming the nanofiber film array are also described. Techniques for forming these structures include placing a suspension of nanofibers and/or nanoparticles on a patterned substrate. A pressure differential is applied, drawing the solvent of the suspension through holes in a mask. The nanofibers collect on an impermeable layer on the mask in a pattern corresponding to the negative features (grooves, holes, trenches) of the mask as the solvent is flowed through the holes.