Modern Technologies of Manufacturing Nonwovens and Cotton's Realistic Scope of Utilization in Nonwovens

Modern nonwoven manufacturing technologies are broadly classified into the so-called “Dry” and “Wet” production lines.  As the names imply, the dry line generally does not involve any liquid and the wet line always involves some kind of liquid, generally water. Further, the manufacturing of nonwovens generally constitute two main processes, viz., 1) preparation of a fibrous web or batt for its in-process stability, and 2) bonding of the web’s constituent fibers for attaining sufficient strength and durability of the nonwoven product.  Depending on the product, there are several techniques and technologies for preparing a stable web and for strongly bonding its constituents.  Today, the most commonly used methods, in the order of their predominance, for preparing a fibrous web are:

1. Spun-bonding  (of synthetic fibers/thermoplastic materials)
   
2. Meltblown (for synthetic fibers/thermoplastic materials)
   
3. Carding and layered crosslapping (for natural and manufactured staple fibers)
   
4. Pneumatic and random assembly of staples fibers (slightly lacks uniformity)
   
5. Wet-laid (mostly for very short fibers, such as pulp)
   

The modern technologies and methods for bonding the web fibers mainly fall under:

1. Mechanical Bonding
   

                  -Needlepunching with barbed needles
-Hydroentangling with high-pressure water jets
-Stitch-through with or without warp-knitting yarns  (rarely used today, but it has a good potential for cotton)
-High-pressure Compressive Calendering (for certain felt-like structures).

 2.      Thermal Bonding
-          spun-bonding
-          meltblown
-          fusible fibers
-          composites containing low-melting powders/fibers.
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 3.      Chemical/Resin Bonding (numerous chemicals and resins)

 4.      Ultrasonic Bonding

 Since cotton fiber is not a fusible fiber, only a few and limited techniques and technologies of preparing and bonding a cotton web or batt can be efficiently selected applied.  And because of this technological limitation, coupled with certain unique characteristics of cotton fiber, it seems that a considerable research and development is needed to expand the scope of cotton utilization in nonwoven products.  This paper will briefly explore the efforts that the USDA-ARS is currently devoting to achieve more utilization of specially the generic, virgin cotton in the nonwovens of today and tomorrow.