Spunlaced Or Hydroentangled Nonwovens Part three of a five-part ...

Tag : carded fabric

Fibers

Spunlacing can be carried out using drylaid - carded or airlaid -or wetlaid webs made of natural or man-made fibers, or blends.Cellulosic fibers are hydrophilic, chemically stable and relativelycolorless. In general, low-micronaire cotton is not recommended forhydroentangled nonwovens because of a higher number of neps andsmall bundles of entangled fibers, resulting in unsightly-appearingfabric. In spite of this, fabrics made with lower-micronaire fibershow higher strength, probably caused by a higher number of finefibers and greater surface area. In addition, greige cotton hasbeen used in spunlace technology. It has been shown that theabsorbency rate increases with increasing hydroentangling energy.This is the result of oil and wax removal from the fiber surface.These nonwovens subsequently can be bleached, which should raisethe strength of the fabric.

All success in the competitive, but highly profit-yielding, marketof technical textiles and nonwovens is based on experience andknow-how in traditional textile products manufacturing. Some cottonspinners already are working successfully with spunlacing lines. Astraditional textile manufacturers, they know how to handle fibers,so there basically is no big difference between spinning andnonwovens, at least at the start of the production process. Fibersare fibers; a card is a card.

Properties

High-water-pressure machines mostly are used because when usinghigh pressure, energy can be delivered into a web with fewer waterneedles and less water. This is economically beneficial. Anotherbasic process parameter having influence on the fabric is the speedof the line. If a constant amount of energy is being delivered to afabric, the speed of the fabric determines how much energy is goingto be absorbed per fabric unit area. Logically, the higher the linespeeds, the less the energy that is absorbed by the fabric and thelower the fabric strength that is achieved.

Spunlaced fabrics show high drape, softness and comfortable handbecause increased fiber entanglement leads to increased strengthwithout an increase in shear modulus. The softness of the fabric isexplained by the fact that the entangled structures are morecompressible than bonded ones as well as having mobility andpartial alignment of fibers in the thickness direction. The absenceof a binder is seen to result in a fabric with more textile-likeappearance.

The substrate texture seems to have an important influence on theproduct. The size of perforations is usually measured in mesh,which is the count of wires per inch of the substrate. Imposing thesame energy into two webs with different substrate meshes, thefiner substrate yields a stronger product resulting from finersupport. A coarser wire support, say, 20 mesh, results in a bulkierproduct with more permeability, but less strength. Water removalfrom the fabric has been shown to be dependent on the mesh of thesupport belt.

System Suppliers

For spunlacing, there are two main technology suppliers on themarket: Germany-based Fleissner GmbH, a daughter company ofGermany-based Trützschler GmbH & Co. KG; and France-basedRieter Perfojet, a subsidiary of Switzerland-based Rieter TextileSystems. Both companies have a lot of experience and are able tosupply turnkey installations. It is of utmost importance to installcompatible lines without any production problems along thedifferent stages of production. Both companies have their own pilotlines - at Egelsbach, Germany, for Fleissner, and at Montbonnot,France, for Rieter Perfojet. The technical centers enable trials tobe performed to ensure the equipment configuration meets therelevant needs.