Materials used in the spunlace technology
As previously mentioned, hydroentanglement could be carried out using dry-laid (carded or air-laid) or wet-laid webs as a precursor. Most commonly, precursors are mixtures of cellulose such as viscose, rayon, plant fibre, wood pulpand or man-made fibers (PET, nylon, acrylics, Kevlar(P84, (imide) etc). In addition, Asahi Chemical Industry has used very fine fibers produced from splittable composite fibers to produce hydroentangled substrates for synthetic suede leather products.
In general, cellulosic fibers are preferred for their high strength, pliability, plastic deformation resistance and water insolubility. Cellulosic fibers are hydrophilic, chemically stable and relatively colorless. Another advantage is that cellulose has an inherent bonding ability caused by a high content of hydroxyl groups, which attract water molecules. As the water evaporates from the fabric, the hydroxyl groups on fiber surface link together by hydrogen bonds.
TInfluence of cotton micronaire on fabric properties has been studied. Generally, low micronaire cotton is not recommended for hydroentangled nonwovens because of higher number of neps and small bundles of entangled fibers, resulting in unsightly appearing fabric. In spite of this, fabrics made with lower micronaire fiber show higher strength, probably caused by a higher number of fine fibers and greater surface area.
Also, greige cotton has been used in spunlacing technology. It has been shown that the absorbency rate increases with increasing hydroentangling energy. This is the result of oil and wax removal from the fiber surface. These nonwovens can be subsequently bleached, which should raise the strength of the fabric.