Hydroentanglement

Hydroentanglement is a bonding process for wet or dry fibrous webs made by either carding, airlaying or wet-laying, the resulting bonded fabric being a nonwoven. It uses fine, high pressure jets of water which penetrate the web, hit the conveyor belt (or "wire" as in papermaking conveyor) and bounce back causing the fibres to entangle.^[1]

Hydroentanglement is sometimes known as spunlacing, this term arising because the early nonwovens were entangled on conveyors with a patterned weave which gave the nonwovens a lacy appearance. It can also be regarded as a two-dimensional equivalent of spinning fibres into yarns prior to weaving. The water pressure has a direct bearing on the gsm, and strength of the web, and very high pressures not only entangle but can also split fibres into micro- and nano-fibres which give the resulting hydroentangled nonwoven a leatherlike or even silky texture. This type of nonwoven can be as strong and tough as woven fabrics made from the same fibres.^[2][1]

Different types of staple length fibers and blends can be used in hydroentangled nonwoven fabrics. Polyester and cellulosic (regenerated cellulosic fibers such as viscose) blend is most commonly used in these fabrics.^[3]

The spun-lace fabrics have variable thickness and properties since they are produced by varying processing parameters such as waterjet pressure, delivery speed, web mass and web composition. Primarily these fabrics are water absorbent and holds many other properties like water retention, water vapor permeability and capillary. They are lightweight , soft, flexible and silky texture. They are disposable and affordable than peers.^[4][5]

Here are the key steps involved in the spunlace nonwoven manufacturing process:^[6]

• Fiber Preparation:

The process starts with the selection of appropriate raw materials. These can include natural fibers like cotton, viscose, or bamboo, as well as synthetic fibers like polyester, polypropylene, or a blend of various fibers.

• Carding:

In this step, the fibers are carded to align them in a parallel orientation. Carding involves passing the fibers through a series of rollers with fine wire teeth, which separate and align the fibers.

• Web Formation:

The aligned fibers are then fed into a machine that creates a loose, fibrous web. This web acts as the starting point for the spunlace process.

• Hydroentangling (Spunlacing):

This is the core step in the spunlace process. The loose fiber web is passed through a series of high-pressure water jets that forcefully spray water onto the fibers. These jets entangle the fibers together, creating a cohesive fabric.The water jets cause the fibers to intertwine, resulting in a nonwoven fabric with specific properties like strength, thickness, and texture.

• Dewatering and Drying:

After the hydroentangling process, excess water is removed from the fabric. This can be done using a combination of mechanical rollers and/or hot air drying, depending on the specific requirements of the final product.

They are suitable for many types of wet wipes, kitchen wipes and aprons. By altering physical properties with lamination, coating, etc. these fabrics offer variety of products suitable in use of hygiene care and medical textiles for instance sanitary napkins, baby wipes, face masks and range of medical gowns used as a part of PPE.^[7][8][9]

• M. G. Kamath; Atul Dahiya; Raghavendra R. Hegde (April 2004). "Spunlace (Hydroentanglement)". University of Tennessee's College of Engineering. Archived from the original on 2013-12-08. Retrieved 2013-11-25.
• Horrocks, Richard A.; Annex, Brian H. (2000). Handbook of Technical Textiles. Elsevier. pp. 150–151. ISBN 9781855738966.