Wipes from hydroentangled Nonwovens

Nonwovens have several merits over woven textiles. They have higher filtration efficiency, better absorbancy and permiability, non directional properties compared to wovens; the process is also cheaper because of ability to process recycled and waste fibres and make composites using wood pulp for making wipes. Among the various methods of making nonwovens, hydroentanglement has the merit that it is ideally suited for cotton, translates the characteristics of fibres into fabric and retains textile character. Chemical bonding polymerises the binder with the fibre to create bonds. Thermal bonding welds the fibres. So with both methods, inter-fibre movement is restricted. The resultant fabrics are therefore stiff, lack drape and textile character. Chemical bonding covers the material with binder and so masks the soft feel and absorbancy of cellulosic fibre. It also causes allergy problems to skin. Thermal boding reduces the strength because of melting of fibre. Hydroentanglement, on the other hand, is free from these drawbacks. Fibre characteristics are fully translated into fabric in this system. Further, products have a high durability and do not easily disintegrate. This is because the entanglement is similar to that achieved by twisting of fibres into yarn. The nonwoven made by hydroentanglement has a textile character similar to knits or wovens.Strength of hydroentangled fabrics are also close to that of woven and knitted materials. Fibres are first opened and carded.Entanglement is achieved by directing fine water jets on to a web emerging from card and supported by a transporting belt. As the water strikes the web, fibres are deflected and entanglement occurs. Very high water pressure of the order of 100-160 bars is used. Production rates are very high with delivery speeds up to 400-500 m/min. Hydroenglement has the merit that it can make cheap wipes by making a sanwich of nonwoven with wood pulp. 3 layer sandwich with wood pulp sanwiched between 2 layers of staple fibre and cosolidated by hydroentanglement, represents an attractive proposition for making cost effective wipes and medical products. Web made from a card is transported on a conveyer lattice. On this a pulp forming unit sprays wood pulp uniformly. Over this a layer of carded web from a second card is laid. The sandwich material then passes through a hydroentanglement unit where entanglement of top and bottom layer of web occurs. the material is then taken through a dryer. Wood pulp thus sandwiched and hydroentangled with a staple fibre web is cheaper compared to 100% staple fibre nonwoven wipes, has a higher thickness and absorbancy and comparable strength. Further, the product has more uniformity as pulp levels out card web irregularities. Production rates upto 400 m/min are possible. Though higher investment is involved in this technology, it pays back rapidly because of low raw material cost, higher productivity and improved properties.