Cross Direction Crease Matrix Channel Geometry Tuning for Chemical Pulp
Cross direction creasing of chemical pulp requires expanding matrix channel width to 1.5 to 1.7 times board caliper plus rule width to prevent liner cracking.
Delamination Bead
Polymer Accumulation
Thickened ridges of plastic or adhesive occurring at the edge of a laminated substrate indicate a separation of layers during the converting process. The delamination bead forms when a coating film pulls away from the paper base and gathers into a localized mass. This defect typically appears during slitting or die cutting operations.
It prevents a smooth finish and can interfere with subsequent printing steps.
Adhesion Failure
Surface tension and cooling rates determine how the molten polymer behaves when the bond fails. If the delamination bead is allowed to harden, it creates a high spot in the finished roll that leads to uneven winding tension. This buildup often forces the layers of paper to stretch or deform.
Pressure from the nip rollers can flatten the bead but rarely restores the structural bond.
Edge Geometry
Precision trimming of the web edges helps to remove areas where the bond is weakest. A delamination bead is more common in structures involving high density polyethylene or complex barrier films. Adjusting the corona treatment levels on the paper surface improves the primary adhesion and stops the film from retracting.
Monitoring the temperature of the extrudate prevents the material from becoming too brittle or too liquid at the exit point. This precise thermal control combined with consistent edge control minimizes the risk of this defect reaching the customer.