Adhesive Failure
The splitting of the glued joint along the side of a folded carton under mechanical tension describes a critical failure that compromises the integrity of the packaging. This side seam delamination occurs when the adhesive fails to bond properly with the paperboard surface. In high-speed packaging lines, such failures can cause the carton to burst open during the filling phase.
Fiber Separation
A strong glue joint must be stronger than the internal bonding strength of the board itself. When side seam delamination happens, it indicates that either the glue did not penetrate the board or the paperboard plies have separated under stress. To prevent this, converters must ensure that the adhesive penetrates through the surface layer to create a deep fiber bond.
This deep fiber bond ensures that any structural failure occurs within the paperboard matrix rather than at the glue line.
Surface Coating
Polyethylene or aqueous barriers applied to paperboard surfaces can prevent the glue from wetting the fibers. If these coatings are not removed or treated using corona discharge, the adhesive cannot form a secure bond, leading to seam failure. Standard tests are performed on finished cartons to measure the force required to pull the seam apart.
