The purpose of the present invention is to provide an electret fiber sheet that has high collection performance and that is suitably used in an air filter, etc. The present invention is an electret fiber sheet configured from polyolefin-based resin fibers comprising a polyolefin-based resin composition containing a high-crystalline polyolefin resin and a low-crystalline polyolefin resin, wherein the mass ratio of the low-crystalline polyolefin resin in the polyolefin-based resin composition is 0.5-10 mass % (inclusive) relative to the total mass of the high-crystalline polyolefin-based resin and the low-crystalline polyolefin resin, and a hindered-amine-based compound is included in the electret fiber sheet in an amount of 0.1-5.0 mass % (inclusive).

A pleated multilayer air filter assembly including a primary filtration layer and a prefilter layer that are bonded to each other and are co-pleated with each other. The primary filtration layer includes meltblown electret fibers. The prefilter layer includes meltspun, spunbonded electret fibers that comprise a radially outer surface comprising polymethylpentene. The ratio of Effective Fiber Diameter of the fibers of the primary filtration layer to Effective Fiber Diameter of the fibers of the primary filtration layer is at least 1.5.

The present disclosure relates to a method for manufacturing an air filtration material, in which the porous metallic support is treated with at least one chemical agent to improve adherence of the electrospun nanofibers. The air filtration material obtained from such method comprises nanoparticle photocatalysts, wherein the nanoparticle photocatalysts are embedded in the electrospun nanofibers and part of the nanoparticle photocatalysts is exposed at the surface of the electrospun nanofibers through nanopores. An air filtration device, comprising the air filtration material, a UV LED and a power source. A method of using the air filtration material wherein an air flow passes through the air filtration material, wherein the air flow has a pollutant content before passing through the material, in order to decrease the air pollutant content. The nanoparticle photocatalysts inactivate or kill the pathogens when the device is in operation.

The present disclosure provides devices and methods for filtering a fluid. An example device can include a first end configured to be joined to a first segment of a pipe. The first end can include a first opening for receiving the fluid. The device can also include a second end configured to be joined to a second segment of the pipe. The second end can include a second opening for transmitting the fluid. A filtering segment can be disposed between the first end and the second end. The filtering segment can include a plurality of fiber filters oriented substantially perpendicular to a direction of flow of the fluid in the pipe. A fiber filter of the plurality of fiber filters can include a mycomaterial and a carrier material configured to provide nutrients to the mycomaterial.

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 provided stretched porous polytetrafluoroethylene membrane has an air permeability of 4 cm.sup.3/(sec.Math.cm.sup.2) or more, as expressed in terms of Frazier air permeability, in a thickness direction, and has a total cohesion of 1.9 (N/20 mm).sup.2 or more, the total cohesion being expressed by a product of a peel cohesion in a first in-plane direction and a peel cohesion in a second in-plane direction perpendicular to the first direction. The above stretched porous membrane is highly air-permeable and, for example, when included in a filter member, being less likely to suffer breakage at the time of handling the member or placing the member on a housing or the like.

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).

A method for ultra-hydrophilic surface treatment of a polymer fiber substrate according to the present invention comprises the steps of: forming a thermosetting coating layer on the surface of a polymer substrate; forming a carboxylate group (—COO—) on the surface of the thermosetting coating layer; forming an amide bond (—CONH—) between the thermosetting coating layer and hydrogel monomers; and forming a hydrophilic polymer layer by crosslinking the hydrogel monomers.

A secondary filter element for a filter system for filtering a gaseous fluid, in particular for a self-cleaning intake air filter system of a motor, has a filter medium which in the intended operation is flowed through by the fluid from an intended inflow side to an intended outflow side. The secondary filter element has a support element covering the filter medium at the intended inflow side. A filter system with such a secondary filter element is provided.

The invention provides a vacuum cleaner filter bag, comprising a wall enclosing an interior and made of an air-permeable material and an inlet opening introduced into the wall, characterized in that the air-permeable material comprises at least one layer of a nonwoven fabric which comprises powdery and/or fibrous recycled material from the production of textiles, in particular cotton textiles, and/or from wool shearing and/or seed fibers.