Personal hygiene applications – from diapers to fem care – are specially designed for absorbency and comfort. In addition, consumers expect high quality from their purchases. Nonwoven applications provide specific functions such as absorbency, stretch, softness, strength and cushioning. To keep up with demand, personal hygiene manufacturers rely on hot melt adhesives to assure a strong bond in their products. These manufacturers employ spray adhesive application as a critical component of their finished good production.
Hot melt spray adhesives are dispensed by manipulating a continuous bead of adhesive into a pattern with compressed air. To maximize machine uptime, it is necessary to understand how to establish a robust process and resolve application issues. Some common process challenges are:
- Overspray – Areas of the production line become coated with adhesive, due to portions of the spray pattern not reaching the substrate
- Poor coverage – Machine direction gaps/voids are present, rather than the desired uniform coating of the substrate
- Bleed-through – Adhesive passes through the substrate and contacts the underlying surface
- Poor intermittent performance – Adhesive trails into the gap between the end of one pattern and the start of the next
Each of these issues could be tied to either an incorrect process setting or a system component malfunction. With the multitude of existing spray technologies, understanding common requirements helps resolve process issues and in turn leads to cleaner production lines with increased up-time.
Understanding Hot Melt Spray Adhesive Process Elements
Understanding how to maintain operating consistency is important. Each equipment manufacturer has best practices to keep the machinery working efficiently. Hot melt spray adhesive issues can result from an over-reliance on generalized guidelines. These are useful in establishing a starting point; however, it is important to gain a strong understanding of how the multiple variables may impact the process and lead to solutions.