A system and method for making electret media is presently provided. The method involves placing a piezoelectric material adjacent a media and applying a mechanical stress to the piezoelectric material and thereby transferring an electric charge from the piezoelectric material to the media and making the electret media. The system is configured to place the piezoelectric material adjacent the media and to apply mechanical stress to the piezoelectric material.

An object is to provide a blood processing filter favorable in both of the effectiveness (leukocyte removing performance) and the safety (reduction in the amount of elutable substances). The object can be achieved by a blood processing filter comprising a filtration medium including a polyester fiber, wherein a surface area of the filtration medium is 6.0 m.sup.2 or more, and a maximum absorbance of an aqueous extract of the blood processing filter in the range from 240 to 245 nm is 0.03 or less.

A nonwoven fabric, including fibers, in which the fibers have an elongational viscosity, as measured under conditions at an elongational strain rate of 2.5×10.sup.2 (1/s) and a temperature of 160° C., of from 430 Pa.Math.s to 1200 Pa.Math.s, and a ratio of the elongational viscosity (Pa.Math.s) to a shear viscosity (Pa.Math.s) of the fiber, as measured under conditions at a shear strain rate of 2.5×10.sup.2 (1/s) and a temperature of 160° C., is from 35 to 65.

Charged polymeric webs, such as electret webs, include a thermoplastic resin and a charge-enhancing additive. The additives are substituted heterocyclic thiolate salts. The heterocyclic thiolate salt has 2 nitrogen groups and a third group that may be an NH, N—NH.sub.2, O, or S group. The substituent group is an aromatic or heterocyclic aromatic group. The electret webs may be a non-woven fibrous web or a film. The electret webs are suitable for use as filter media.

The present invention has an object to provide a blood processing filter that is excellent in the filtration rate. The object can be solved by a blood processing filter comprising a container having an inlet and an outlet for blood, and a filter medium disposed between the inlet and the outlet of the container, wherein the filter medium comprises a filter element, an average thickness of the filter medium is 7 to 12 mm, and a standard deviation in thickness of the filter medium is 0.30 to 0.80 mm.

A gas filtering medium is composed of hydrophobic polyester fiber as from 20-80% by total weight of textile fibers and 80-20% by total weight of hydrophilic textile fibers and a microfibrillated cellulose fiber in a weight/weight ratio of 1.5-8.5/100 parts by weight of total textile fiber.

The present disclosure relates to an anti-droplet mask filter and an anti-droplet mask comprising the same, and more particularly, to a hydrophobic filter having ridges and an anti-droplet mask comprising the same. The present disclosure is directed to providing a mask filter with improved water repellency performance for effectively preventing the spread of acute respiratory syndrome virus infections.

The super water-repellent anti-droplet nonwoven filter of the present disclosure shows superhydrophobicity with the surface contact angle of 160° or more due to the ridges that form a nanopatterned structure on the surface of hydrophobic fibers and the surface of bonding portions, thereby preventing the adsorption of droplets onto the surface of the filter. Additionally, the super water-repellent anti-droplet nonwoven filter of the present disclosure can capture ultrafine particles such as aerosols due to the nanopatterned structure on the surface of the super water-repellent anti-droplet nonwoven filter.

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.

A filter media construct includes a plurality of flexible laminas joined in a stack, each lamina including an array of nanofibers extending from a surface thereof. Each lamina is configured to be permeable to a fluid such that the fluid can flow through each lamina normal to the surface thereof and in any direction along at least a portion of said surface when the fluid is flowed through the construct. The laminas can include a plurality of perforations extending therethrough such that the fluid flows through at least some of the perforations of the laminas when the fluid is flowed through the construct. A contaminant contained in the fluid is at least partially filtered from the fluid by the nanofibers when the fluid is flowed along the surface of any lamina or into or through the perforations.

Provided is a filter medium. A filter medium according to an embodiment of the present invention comprises: a first porous support body which has been electrostatically treated; and a nanofiber web which is disposed on one surface of the first support body and formed by accumulating nanofibers. Accordingly, excellent air filtering efficiency is obtained even for fine dust of PM 2.5 or below, and furthermore, deterioration in air filtering efficiency may be prevented or minimized even when usage is extended for a long period of time. Therefore, the filter medium and the composite filter according to an embodiment of the present invention can be widely utilized as media of filters for various air filtering devices.