The Development of Hydroentanglement (Spunlace) Nonwoven Fabric

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Spunlace is also known as hydroentanglement or hydro-jet. The jet spraying method uses high-speed and high-pressure water to impact the fiber web. This principle was developed by Dupont and Chicopee back in the late 1950s and early 1960s. It was a relatively new nonwoven processing technology in the 20th century.

 
Fiber, the product does not use adhesives, does not lint, does not shed, the product is hygroscopic, soft, high strength, and feels good.
 
Hydroentanglement Process
Like the process principle of needle-punched, spunlace nonwoven fabrics use high-pressure water flow to form a "water needle," acting like acupuncture.  

1. The web is fed into a row or multiple rows of highly pressurized water jets closely spaced together.
2. The high-pressure water flows through the spunlace head and the jet plate to form a continuous circular high-pressure water needle that regularly impacts the web. During the water needle process, fibers are brought into the bottom of the net from the surface, producing a tangle between fibers.
3. The water column bounces to the opposite side of the web. The web is then punctured with high force by the water needle.
4. The entanglement produces a reinforcing effect, resulting in twisting and entangling fibers forming a spunlace nonwoven fabric. The water must flow sufficiently to attain the necessary condition of the spunlace nonwoven material.

 
The required speed and pressure of the water needle directly affect the web that will determine product characteristics.  If the web is carried on a support having a patterned structure, the hydroentanglement process may leave a permanent pattern in the web.
 
Water Requirements:
Water quality is essential as there should be no impurities that may block the circulating water system.  Water quality can also cause uneven color and yellowing of the spunlace result. Water characteristics should be as follows:
• Large amount of water
• No impurities or organic materials
• Neutral in pH
 
The full spunlace process:
•Fiber web formation - pre-wet - multiple spunlace on the front and back
•Reinforcement - pattern spunlace - dehydration - pre-drying - after finishing
•Treatment (printing, dipping, coloring, sizing, etc.) – web drying
•Shaping - slitting - winding - packaging.
 
In the spunlace production line, spunlace reinforcement equipment is the key.  It is composed of a spunlace head (i.e., a water jet), a suction.
The water circulation and treatment system are consisting of a cavity with water passages and a water spray plate. The head is a vital part of the cylindrical water needle that produces high speed and high pressure.
Braided by stainless steel wire, polyamide or polyester monofilament
is woven and can form different structures, patterns, and textures. 
 
Raw Materials for Spunlace
The choice of fibers may vary from natural to synthetic fibers.
• Natural Fibers:
Cellulose fiber: viscose fiber, soluble fiber, cotton.  It has good moisture absorption, soft hand feeling, no allergic reaction to human skin contact. It has the characteristics of natural biodegradation, suitable for medical sanitary materials, wet wipes, and other disposable materials.
The cotton spunlace produced by Wenjian Medical Group Woven medical and health materials are products developed for cotton characteristics. The group is under the leadership of the China Industrial Textile Industry Association.
 

• Synthetic chemical fibers:

Fibers polyester, nylon, acrylic, nylon, polypropylene, etc., have high strength and good elasticity and can be used for water barbed nonwoven fabric.  The fiber characteristics provide strength and elongation, such as synthetic leather base fabric, clothing fusible interlining, various covering materials that can be used independently or mixed with other fibers.
 
• Special fibers:
Wood pulp fiber, Aramid fiber, glass fiber, silk fiber, green poly fibers such as lactic acid fiber, and chitin fiber. Type of threads that have high strength and high performance.  Wood pulp fiber is commonly used as feminine sanitary napkins, pads baby and adult diaper due to its high moisture absorption performance after mixing with other fibers.
 
Silk fibers contain amino acids needed by the human body.  It is excellent for moisture absorption and breathability, produced as medical gauze and facial mask sheets.