According to ASTM D1117-80, non-woven fabric is defined as the fibrous assembly or film whose fibers have been bonded together by physical, chemical, or mechanical means or through the use of proper moisture or heat rather than by spinning, weaving, and braiding.

Non-woven fabric is a molded product with planar structure made by interweaving natural, chemical, and metal fibers according to their mutual characteristics to form a web in the shape of a sheet and bonding them together by mechanical or physical means.

■ Process

Principles of SPUNBOND molding

Spunbond is called filament fiber non-woven fabric since it uses filaments. The filament spun out of the extruder is elongated and stacked on the conveyor. The stacked web is then bonded to the calendar roll and wound after undergoing the transfer process.

Non-woven Fiber Molding Device

The spunbond molding device performs web forming processes such as spinning, elongation opening and capturing process.

Spinning Process

The spinning process involves discharging molten polymer as a filament into the air through the nozzle. Both melt and wet spinning are used in the process, but the former is most common.

Elongation Process

In the elongation process, the tensile strength of the discharged filament increases as it is elongated through the high-speed air roll or other rolls having different revolution speeds.

Opening Process

The opening process involves uniformly separating the elongated filament, which greatly affects the performance of non-woven fabric. The filament opening process includes electrostatic charge, impingement plate, and air current diffusion methods. The electrostatic charge method involves building up the same static charge in each filament to induce an opening using its repulsive force. The impingement plate method involves having the filament hit the impingement plate to be dispersed. The air current diffusion method entails installing an air current diffusion device at the vent of high-speed air fluid to diffuse air current aerodynamically, thereby putting the filament on a diffused air current to induce opening.

Capturing Process

In the capturing process, the opened filament is deposited on an air-permeable screen conveyor or a screen drum. The web formed on the screen is sucked in from the screen surface to prevent it from being blown away by the high-speed air current.

■ Non-woven fabric Classification by Manufacturing Method