Manufacturing processes
Staple non-wovens
Staple non-wovens are made in two steps. Fibers are first spun, cut to a few centimeters length, and put into bales. These bales are then dispersed on a conveyor belt, and the fibers are spread in a uniform web by a wetlaid process or by carding.
Spunlaid non-wovens
Spunlaid non-wovens are made in one continuous process. Fibers are spun and directly dispersed in a web by deflectors. This technique leads to faster belt speeds, and cheaper costs. Several variants of this concept are available, but the leading technology is the Reicofil machinery, manufactured by Reifenhaüser (Germany).
Bonding
Both staple and spunlaid non-wovens would have no mechanical resistance per se without the bonding step. Several methods can be used:
- thermal bonding: calendering through heated rollers (called spunbond when combined with spunlaid)
- hydro-entanglement: mechanical intertwining of fibers by water jets
- needlefelt: mechanical intertwining of fibers by needles