Nonwovens are typically manufactured by putting small fibres together in the form of a sheet or web (similar to paper on a paper machine), and then binding them either mechanically (as in the case of felt, by interlocking them with serrated needles such that the inter-fibre friction results in a stronger fabric), with an adhesive, or thermally (by applying binder (in the form of powder, paste, or polymer melt) and melting the binder onto the web by increasing temperature).
Staple nonwovens are made in 2 steps. Fibres are first spun, cut to a few centimetres length, and put into bales. These bales are then dispersed on a conveyor belt, and the fibres are spread in a uniform web by a wetlaid process or by carding. Wetlaid operations typically use 1/4" to 3/4" long fibres, but sometimes longer if the fibre is stiff or thick. Carding operations typically use ~1.5" long fibres. Rayon used to be a common fibre in nonwovens, now greatly replaced by PET and PP. Fibreglass is wetlaid into mats for use in roofing and shingles. Synthetic fibre blends are wetlaid along with cellulose for single-use fabrics. Staple nonwovens are bonded by using either resin or thermally. Bonding can be throughout the web by resin saturation or overall thermal bonding or in a distinct pattern via resin printing or thermal spot bonding. Conforming with staple fibres usually refers to a combination with meltblown, often used in high-end textile insulations. Melt Blown non wovens are produced by extruding melted polymer fibres through a spin net or die consisting of up to 40 holes per inch to form long thin fibres which are stretched and cooled by passing hot air over the fibres as they fall from the die.The resultant web is collected into rolls and subsequently converted to finished products.The extremely fine fibres typically polypropylene differ from other extrusions
particularly spun bond in that they have low intrinsic strength but much smaller size offering key properties.Often melt blown is added to spun bond to form SM or SMS webs, which are strong and offer the intrinsic benefits of fine fibres such as fine filtration, low pressure drop as used in face masks or filters and physical benefits such as acoustic insulation as used in dishwashers. One of the largest users of SM and SMS materials is the disposable diaper and feminine care industry.
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