Abstract: Described herein is a thermoplastic core-sheath fiber. The thermoplastic core-sheath fiber comprises a core having a coextensive sheath layer disposed thereon, wherein the core comprises a first polymeric resin and an electrostatic charge enhancing additive, and the sheath layer comprising a second polymeric resin, with the proviso that if the second polymeric resin comprises poly(4-methyl-1-pentene), then the second polymeric resin does not comprise 100 wt % of poly(4-methyl-1-pentene). These thermoplastic core-sheath fibers can be used in filtering applications.

Abstract: A thermoplastic core-sheath fiber comprises: a polymer fiber core having a coextensive sheath layer disposed thereon, and an electrostatic charge enhancing additive. The sheath layer may comprise poly(4-methyl-1-pentene) and the fiber core and the sheath layer have different compositions. At least one of the fiber core or the sheath layer comprises an electret charge. A nonwoven fibrous web comprising the core-sheath fibers and a respirator including the nonwoven fibrous web are also disclosed.

Abstract: A filter assembly comprises an air filter medium and a prefilter medium. The prefilter medium comprises a second nonwoven fibrous web comprising poly(4-methylpentene) and an electrostatic charging additive and has a second electret charge. The filter assembly is configured such that air passing through the prefilter is directed through the air filter medium. A respirator includes the filter assembly. A prefilter assembly comprises a third nonwoven fibrous web retained by a prefilter frame. The third nonwoven fibrous web comprises: core-sheath fiber comprising a fiber core having a poly(4-methylpentene) sheath layer disposed thereon; and an electrostatic charging additive, wherein the electrostatic charging additive is contained in at least one of the fiber core or the sheath layer. The third nonwoven fibrous web has a third electret charge.

Abstract: The present disclosure relates to multi-layer composite articles including at least two nonwoven web layers. Each or the layers may be a spunbonded web, and each may include biodegradable materials. The multi-layered composites of the present disclosure are particularly well suited for air filtration, as they can combine a high dust holding capacity with sufficient strength, dimensional stability, and a relatively low pressure drop.

Abstract: Nonwoven webs including one or more semi-continuous filaments made of a mixture including from about 50% w/w to about 99% w/w of at least one crystalline polyolefin (co)polymer, and from about 1% w/w to about 40% w/w of at least one hydrocarbon tackifier resin. The at least one semi-continuous filament exhibits molecular orientation, and at least one of the crystalline polyolefin (co)polymer or the nonwoven web exhibits a Heat of Fusion measured using Differential Scanning Calorimetry of greater than 50 Joules/g. A process for making the semi-continuous filaments and nonwoven webs is also disclosed.

Abstract: A web of nonwoven fabric suitable for, e.g., the loop portion of a hook-and-loop fastening system. The method for making this material relies on differential shrinkage of different layers to cause the loops to self-form. The method is robust and simpler than that previously used for similar constructions.

Abstract: Spunbonded electret webs comprising polylactic acid fibers, in which at least some of the polylactic acid fibers are meltspun, drawn, charged fibers that include charging additive; and, methods of making such fibers and webs.

Abstract: Spunbonded electret webs comprising polylactic acid fibers, in which at least some of the polylactic acid fibers are meltspun, drawn, charged fibers that include charging additive; and, methods of making such fibers and webs.

Abstract: High loft nonwoven webs including a population of substantially continuous mono-component melt-spun filaments, wherein the nonwoven web exhibits a Solidity of less than eight percent with a weight normalized cross direction (CD) tensile greater than 10 Newtons per 100 grams per square meter of web weight (10 N/100 gsm), and wherein the nonwoven web is substantially free of gap-formed fibers, crimped fibers, staple fibers, and bi-component fibers. High loft spun-bond nonwoven webs can be advantageously used in filtration articles. Methods of making high loft spun-bond nonwoven webs, and filtration articles including high loft spun-bond webs made according to the methods, are also disclosed.