“Spun bonding is one of the most popular methods of producing polymer-laid nonwovens. This process is based on the melt spinning technique. The melt is forced by spin pumps through a spinneret having a large number of holes. The quench air ducts, located below the spinneret block, continuously supply the conditioned air to cool the filaments. There is also a continuous supply of auxiliary room temperature air. Over the line's entire working width, ventilator generated under-pressure sucks the filaments and mixed air down from the spinnerets and cooling chambers.”

“The through a venture (high velocity low pressure zone) to a distributing chamber, which affects fanning and entanglement of the filaments. Finally, the filaments are deposited as a random web on a moving sieve belt. The randomness is imparted by the turbulence in the air stream, but there is a small bias in the machine direction due to some directionality imparted by the moving belt. The section below the sieve belt enhances the lay down of the filaments. The conveyor belt then carries the spun bonded web to the bonding zone. The web is then bonded either thermally, mechanically or chemically, depending on the material and the desired properties in the final fabric. Thermal point bonding is the most commonly used technique for many applications.”

(Gopalakrishnan, Spun Bonding, 6/1/2011)

“A spunbond web is normally made by depositing fibers on a foraminous deposition belt. The fibers are often made of a thermoplastic synthetic resin. Generally and preferably, a suction device is provided under the foraminous deposition belt to draw air down through the foraminous deposition belt in the area where the fibers are deposited.”

“An apparatus of the type described above is known in practice in various embodiments. The foraminous deposition belt is usually guided over several rollers so that there is substantial contact between the roller surfaces and the deposition belt. Once the fibers are deposited on the foraminous deposition belt, some of them are sucked through the belt, e.g. between the warp and weft of the belt. These are termed "throughshots."

“The known apparatus has in the transfer area where the web is separated from the belt an output roller over which the deposition belt passes through a relatively large angle. In this output area, the spunbond web is usually transferred from the deposition belt to a calender in which it is compacted, so that the web moves off in its horizontal plane while the underlying belt pulls downward away from it as it moves around the output roller. As a result of the separation of the spunbond web from the belt, with the throughshot filaments passing through both, the bridging fibers are torn off, and the torn-off fibers are freed to go into the air as fiber waste (so-called "snow"). The fibers remaining between the warp and weft threads of the belt are pressed into and onto the belt due to the interaction of the belt with the rollers of the apparatus, thus forming undesired adhesion points for the spunbond web on the belt. This contamination of the belt has an adverse effect on the quality of the spun non-woven materials produced.”

(Kuhn, US Patent 7,849,902, 12/14/2010)

Materials
Nonwoven Fabrics
Textiles
 

Recent US Patents

Comments