Filter media incorporating one or more filtration layers that include fibers including fiber portions orientated at a non-zero angle with respect to a surface of the filtration layer are provided. In some embodiments, at least a part of the fiber portions are positioned at an angle of at least 20 degrees (e.g., between 46 degrees and 90 degrees, or between 61 degrees and 90 degrees) with respect to a surface of the filtration layer or an outer or cover layer of the media. This orientation of fiber portions may result in an increased efficiency (e.g., average efficiency and/or initial efficiency) compared to similar filter media that do not include such oriented fiber portions.

A method for producing a 3D sponge based on nanofibers includes the processing steps of producing nanofiber based material, cutting the nanofiber based material in small pieces, suspending the small pieces into a wetting non-dissolving liquid, homogenizing the suspension to obtain a slurry with separated short nanofibers, freezing the slurry at a controlled rate and generating a solid templated 3D network of short nanofibers, and thermally, physically or chemically cross-linking the short nanofibers to improve the mechanical stability of the produced sponge.

The present invention generally relates to a dual density air filtration media that comprises a plurality of nanofibers layers formed from nanofibers having different fiber diameters. Due to the presence of these multiple nanofiber layers with different nanofiber diameters, the resulting filtration media of the present invention comprises a gradient density. In particular, the present invention uses a novel combination of two or more layers of nanofibers made via an electrospinning process, wherein the nanofiber layers made up from different fiber sizes are strategically applied to a cellulose or synthetic base material or substrate, to thereby maximize the filtration efficiency and dust holding capacity of the resulting filtration media.

A polymer, applications thereof, and method of making a nanofiber nonwoven product is disclosed which includes: providing a spinnable polyamide polymer composition comprising a solution of a polyamide in a suitable solvent, wherein the polyamide has a Relative Viscosity of from 30-300; a basis weight greater than 1 gm/m.sup.2, solution-spinning the polyamide polymer composition into a plurality of nanofibers having an average fiber diameter of less than 1 micron (1000 nanometers); and forming the nanofibers into said nonwoven product which thereby has an average nanofiber diameter of less than 1 micron (1000 nanometers). Preferably, the nonwoven product is solution-spun from a process selected from (i) centrifugal spinning using a rotating spinneret or (ii) 2-phase propellant-gas spinning including extruding the polyamide polymer composition in liquid form with pressurized gas through a fiber-forming channel. Suitable solvents include formic acid, sulfuric acid, trifluoroacetic acid, hexafluoroisopropanol (HFIP) and phenols including m-cresol.

Spun bond nonwoven fabric comprises, as constituting filament, conjugate polyester continuous filaments having a cross-sectional shape of a nearly Y4-like shape. The continuous filament is composed of a nearly V-shape portion 6 in the nearly Y4-like shape, formed from low melting point polyester, and the other nearly+shape portion 5 therein, formed from high melting point polyester. The continuous filaments are heat-bonded with each other by the low melting point polyester. The spun bond nonwoven fabric is bonded by a powder type or spider web type hot melt adhesive agent with the melt blown nonwoven fabric.

Filter media are described. The filter media may include multiple layers. In some embodiments, the filter media include a nanofiber layer adhered to another layer. In some embodiments, the layer to which the nanofiber layer is adhered is formed of multiple fiber types (e.g., fibers that give rise to structures having different air permeabilities and/or pressure drops). In some embodiments, the nanofiber layer is adhered to a single-phase or a multi-phase layer. In some embodiments, the nanofiber layer is manufactured from a meltblown process. The filter media may be designed to have advantageous properties including, in some cases, a high dust particle capture efficiency and/or a high dust holding capacity.

Disclosed here is a composite filter media having at least one nanofiber layer bonded to a substrate layer, the at least one nanofiber layer optionally having a plurality of nanofibers having a geometric mean diameter of less than or equal to 0.5 m, the at least one nanofiber layer having a thickness of about 1-100 m.

A present invention is directed to a laminated filtration media comprising a nanofiber coating applied onto a synthetic substrate. Generally, the laminated filtration media can be produced by applying the nanofiber layer onto the synthetic substrate via an electrospinning process and then thermo-mechanically bonding the nanofiber layer onto the synthetic substrate via a thermal bonding process. The laminated filtration media exhibits superior durability and can be used in a wide array of air filtration applications.

A filtration barrier comprises at least one barrier layer which includes polymeric nanofibers interlaced with microfibers, and at least one substrate layer which includes polymeric microfibers. The filtration barrier can be made by electrospinning process.

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.