Water impermeable, air permeable membrane assemblies are described herein. In some embodiments, the assemblies include a polymer membrane and at least one support structure. Certain assemblies are configured to provide an acoustic impedance having phase angle of +45 degrees to −45 over a frequency range of 50 to 20,000 Hz.

A single-layer spunbonded air-filtration web including meltspun autogenously bonded electret fibers with an Actual Fiber Diameter of from 3.0 microns to 15 microns. The air-filtration web exhibits a ratio of mean flow pore size to pore size range of from 0.55 to 2.5. Also disclosed are methods of making such webs, and methods of using such webs to perform air filtration.

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.

Various high performance, high efficiency filter media are provided that are cost effective and easy to manufacture. In particular, various filter media are provided having at least one layer with a waved configuration that results in an increased surface area, thereby enhancing various properties of the filter media. The filter media can be used to form a variety of filter elements for use in various applications.

Filter media having a relatively small pore size and related components, systems, and methods associated therewith are provided. The filter media may include a fibrous efficiency layer, a fibrous support layer, and a third layer adjacent to the efficiency layer. The efficiency layer may impart a relatively homogeneous pore structure to the filter media without adding substantial bulk to the filter media. The support layer may promote the homogeneity of the pore structure. For example, the support layer may prevent and/or minimize defects in the relatively thin efficiency layer that may result from manufacturing and/or processing. The third layer may serve to impart beneficial filtration (e.g., efficiency, dust holding capacity) and/or non-filtration (e.g., layer protection) properties to the filter media without adversely affecting one or more properties of the filter media. Filter media, as described herein, may be particularly well-suited for applications that involve liquid filtration, amongst other applications.

Provided are a self-cleaning air filtering material and a preparation method therefor. The air filtering material comprises: a submicron fiber layer (2) at an inflow surface for surface filtration, a supporting area (3) for supporting and a mixed area (5) between the submicron fiber layer (2) and the supporting area (3), wherein the mixed area (5) is formed by contacting and mixing part of the fibers in the submicron fiber layer (2) and the supporting area (3) with each other during the one-step formation of the submicron fiber layer (2) and the supporting area (3) by passing through a double-layer headbox.

An air filtering element, for example of a ventilation system, such as an air ventilation system of a vehicle passenger compartment, includes a filtering medium (1). The filtering medium (1) has a main layer (10) of non-woven fabric including synthetic base fibers (110) and antimicrobial agents (120) in metal or in a metal compound and/or based on a metal complex and/or based on a metal salt. The main layer (10) of non-woven fabric has a porosity value of between 80% and 95%, preferably between 85% and 95%, preferably between 85% and 93%. In addition, the main layer (10) has hydrophilic behavior, so as to collect and form aggregates of water on which the antimicrobial agents (120) act and perform their antimicrobial action.

Method for preparing a membrane from fibril cellulose includes supplying fibril cellulose dispersion on a filter layer, draining liquid from a fibril cellulose dispersion by the effect of reduced pressure through the filter layer that is impermeable to fibrils of the fibril cellulose but permeable to the liquid to form a membrane sheet on the filter fabric, applying heat on the opposite side of the membrane sheet to the membrane sheet while continuing draining of the liquid through the filter layer by pressure difference over the filter layer, and removing the membrane sheet from the filter layer as a freestanding membrane.

A filter medium is provided. The filter medium according to an embodiment of the present invention comprises a second support body and a nanofiber web layer which are sequentially stacked on each of both surfaces of a first support body, and is a filter medium having a flow path through which a filtrate filtrated in the nanofiber web flows in the direction of the first support body, wherein the nanofiber web has a basis weight of 30 g/m2 or less, the first support body has a basis weight of 250 g/m2 or more, and a thickness of 90% or more of the total thickness of the filter media. Accordingly, even in a backwash process performed at high pressure, as the shape, structural deformation, and damage of the filter medium can be minimized, the use period can be extended. In addition, as the flow path is smoothly secured at high pressure applied at the time of filtration and/or backwashing, the filtration water is quickly discharged to the outside from the inside of the filter medium or the backwashing efficiency is very excellent, and accordingly it is possible to be applied in various ways in various water treatment fields.

A method for controlling fiber cross-alignment in a nanofiber membrane, comprising: providing a multiple segment collector in an electrospinning device including a first and second segment electrically isolated from an intermediate segment positioned between the first and second segment, collectively presenting a cylindrical structure, rotating the cylindrical structure around a longitudinal axis proximate to an electrically charged fiber emitter; electrically grounding or charging edge conductors circumferentially resident on the first and second segment, maintaining intermediate collector electrically neutral; dispensing electrospun fiber toward the collector, the fiber attaching to edge conductors and spanning the separation space between edge conductors; attracting electrospun fiber attached to the edge conductors to the surface of the cylindrical structure, forming a first fiber layer; increasing or decreasing rotation speed of the cylindrical structure to alter the angular cross-alignment relationship between aligned nanofibers in adjacent layers, the rotation speed being altered to achieve a target relational angle.