a quick peek at the ins and outs of this key bonding technology
By Guy A. Gil
National Sales Manager Chase Machine & Engineering
The uses for nonwovens continue to increase dramatically. Applications include hospital gowns, face masks, hygiene products, wound care, wipes, air and liquid filtration media and many more. New uses continue to be found every day as both nonwoven materials—and the methods and equipment for handling and working with them—improve.
Ultrasonic bonding has opened doors to many new nonwoven product opportunities. For applications that require high loft, softness, breathability and/or high absorption, ultrasonic bonding provides precise bonding without stiffening of material. Ultrasonic laminating and slitting also produce a finished edge without loose fibers, critical for medical applications and filtration media.
There are two major ways to apply ultrasonic bonding: through a plunge mode, for single-strike bonding such as spot welding, button holes and attaching ties and straps; and through a rotary drum for continuous web bonding. Maintaining the integrity of the media while maximizing throughput and production speeds is critical.
Sometimes the products or manufacturing methods require that the nonwoven media be modified in order to make manufacturing a new product possible. One such example is the area of extended pocket air filters (pictured at right) using ultrasonics, where the inconsistencies in nonwoven materials can be a major problem. When using melt blown materials, polymer “pellets” can occasionally turn up in the fibers and get stuck between the ultrasonic horn and anvil, and tear the web.
In addressing this problem, nonwovens manufacturers have greatly improved the consistency and quality of the nonwoven media. Using ultrasonics to manufacture filters eliminates the puncture holes required by conventional sewing with needles and thread, and there are no puncture holes to be sealed.
The ability to modify the structure of nonwovens to adjust porosity, strength, hand and durability creates an almost limitless potential for nonwovens. Production of nonwoven products by ultrasonic bonding, laminating and slitting has improved dramatically as throughput, bond quality and web handling techniques have advanced.