Needle-punched nonwoven fabrics

Needle-punched nonwoven fabrics are made from various fibrous webs (usually carded webs) in which hbres are bonded together mechanically through fibre entanglement and frictions after hne needle barbs repeatedly penetrated through the fibrous web. Needle-punched fabrics have characteristic periodicities in their structural architecture that result from the interaction of fibres with the needle barbs. Fibre segments are reorientated and migrated from the surface of the web towards the interior of the fabric, forming pillars of hbre orientated approximately perpendicular to the plane. 

Anandjivala RD, Boguslavsky L. Development of needle-punched nonwoven fabrics from flax flbers for air filtration applications. Text Res J 2008 78(7) 614—24. 

With the recent continuous developments in the fields of nonwoven fabric formation technologies, their areas of applications are increasing rapidly during these days. Basically, there are three main varieties of nonwoven fabrics in use, namely, spunbond, spunlace, and needle-punch nonwoven fabrics. Sometimes, they are also used in combinations with other form of fabric structures, depending upon the requirements of end use applications [1]. 

Principle appHcations of needle-punched nonwovens for the 1990s include automotive, apparel components, blankets, carpeting, carpet pa dding, coating substrates, filtration, furniture, geotextiles, insulation, roofing substrates, and wall coverings. In 1990, the production of needle-punched fabric was estimated to approach 91,000 t and 606 million square meters (15). 

Spunbonded fabrics have a relatively small percentage of the coated fabric market which is dominated by other nonwovens. Needle-punched nonwovens offer more of the bulk and resiHency required for functionaHty in automotive and furniture seating. 

Pollutant Loading Typical inlet concentrations to cartridge collectors are 1 to 23 grams per cubic meter (g/m ) (0.5 to 10 grains per cubic foot (gr/ft )). Cartridge filters, which utilize synthetic, nonwoven media such as needle punched felts fabricated of polyester or Nomex, are able to handle inlet concentrations up to 57 g/m (25 gr/ft ). 

In nonwoven geotextiles, the fibers are much thinner but far more numerous. The various types are needle-punched, resin-bond, and melt-bond. All contain a labyrinth of randomly oriented fibers that cross one another so that there is no direct line of flow. The fabric must have enough open space to allow liquid to pass through, while simultaneously retaining any upstream movement of particles. The needle-punched nonwoven type is very commonly used as a filter material. 

Pig. 3. Typical stress—strain curves of nonwoven fabrics, where (-thermally bonded nonwoven and (—), needle-punched nonwoven. 

Fabric density of needled hlter could be controlled through needle-punching parameters, such as needling density and penetrahon depth many needle-punched nonwoven hlters are made of multiple layer stractures including various needled nonwoven hbrous layers and reinforcement layers (scrim, woven fabric, lightweight spunbond nonwovens, etc.) to achieve required hltrahon efficiency, compactness, dimension stability, and mechanical robustness." ... 

In a totally different application, the US Forest Service began using needle-punched nonwoven geotextiles as wraparound walls in steep logging terrain in the Pacific Northwest in 1974. The fabric rolls were sometimes delivered by helicopters. Geotextile-reinforced embankments were constructed in Alaska beginning in 1975... 

RoUin, A.L., 1983. Characteristics of needle punched nonwovens and their influence on filtration behaviour in geotextiles. In Proceedings Conference on Nonwoven Fabrics, UMIST, Manchester, UK, 1983. 

Within the plane of a nonwoven material, the fibers may be either completely isotropic or there may be a preferred fiber orientation or alignment usually with respect to a machine or processing direction. In the case of thicker dry-laid nonwovens, fiber orientation may be randomized in the third dimension, ie, that dimension which is perpendicular to the plane of the fabric, by a process known as needle-punching (7). This process serves to bind the fibers in the nonwoven by mechanical interlocking. 

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