The present disclosure includes filter aids comprising expanded perlite and methods for preparation thereof. The perlite used for making the filter aids may be processed by dehydration, expansion, milling, and/or screening. The expanded perlite has a higher density compared to expanded perlite prepared without dehydration.

A laminated polyarylene sulfide heat-resistant filter has a plurality of layers, at least including a first web layer that is a filtering surface, and a second web layer that is a non-filtering surface, the laminated polyarylene sulfide heat-resistant filter being characterized in that the first web layer contains 30 to 70 wt % of polyarylene sulfide fibers having a fineness of 0.5 to 1.2 dtex, and 30 to 70 wt % of polyarylene sulfide fibers having a fineness of 1.3 to 3.0 dtex taking a total of a weight percentages of the first web layer as 100 wt %, wherein the second web layer contains polyarylene sulfide fibers having a fineness of 1.0 to 4.0 dtex.

The present invention relates to a fluororesin porous film in which, based on the total thickness of the fluororesin porous film composed of a single 5 m to 300 m layer, a thickness ratio of nodes distributed on any one surface shows a difference of 5% or more compared to a thickness ratio of nodes distributed on the other surface forming the remaining part, a method for preparing the same, and a vent filter including the porous film.

A nanofiber nonwoven product is disclosed which comprises a polyamide with a relative viscosity from 2 to 330, spun into nanofibers with an average diameter of less than 1000 nanometers (1 micron). In general, the inventive products are prepared by: (a) providing a polyamide composition, wherein the polyamide has a relative viscosity from 2 to 330; (b) melt spinning the polyamide composition into a plurality of nanofibers having an average fiber diameter of less than 1 micron, followed by (c) forming the nanofibers into the product.

A coalescence filter including an inlet for supplying the gas to a filter element present in the coalescing filter, which filter element includes a coalescence medium for coalescing at least one disperse liquid phase during a displacement of a gas through the coalescence medium in a flow direction. The filter element downstream of the coalescence medium includes a drainage medium for draining the at least one coalesced disperse phase leaving the coalescence medium. The filter element contains a barrier layer positioned downstream of the coalescence medium, where the coalescence medium and the barrier layer are held at a distance from each other by one or more spacers to provide a drainage zone in the drainage layer of a drainage medium between a surface of the coalescence medium facing the barrier layer and the barrier layer for draining the coalesced disperse phase in a drainage direction.

A filter medium for filtration of a gaseous medium is provided with a carded nonwoven layer and a filter paper layer arranged as a neighboring filter layer at an outflow side of the carded nonwoven layer. The carded nonwoven layer has a first air permeability and the filter paper layer has a second air permeability, wherein the first air permeability of the carded nonwoven layer is higher than the second air permeability of the filter paper layer. In a filter element with such a filter medium, the filter medium is folded to a folded filter medium with folds with a fold spacing of more than 3.5 mm and a fold height of between 10 mm to 60 mm.

Fine fiber products including fiber webs, as well as related assemblies, systems and methods, are described. In some embodiments, fiber webs described herein may include fine fibers and relatively low amounts of degraded polymer formed during a fiber extrusion process. The fiber webs may be used for filter media applications.

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.

The present disclosure provides styrene/acrylonitrile fine fibers, filter media including styrene/acrylonitrile fine fibers, a recirculation filter including a styrene/acrylonitrile fine fiber or filter media, and methods.

Disclosed are improved polymer materials. Also disclosed are fine fiber materials that can be made from the improved polymeric materials in the form of microfiber and nanofiber structures. The microfiber and nanofiber structures can be used in a variety of useful applications including the formation of filter materials.