Evaluating Machine Direction Anisotropy and Crease Ratios in SBS Board
Evaluating machine direction anisotropy and crease depth ratios in SBS board balances fold integrity against corner springback on high-speed cartoning lines.
Clay Coating Integrity
Barrier Capacity
Mineral layer durability under mechanical stress determines the suitability of coated paperboard for high-speed folding carton conversion. In the packaging industry, clay coating integrity measures how well a refined pigment layer adheres to the paperboard substrate during printing and subsequent processing. This performance prevents dusting in the pressroom and ensures a smooth, continuous barrier for subsequent varnish applications.
Failure Mode
Mechanical degradation occurs when the adhesive binder fails to hold the pigment particles together under tensile or shear stresses. When this occurs, clay coating integrity is compromised, leading to pick-out defects where ink tack pulls small fragments of the coating away from the board. This issue ruins print quality and contaminates the ink fountain.
In carton converting, the pigment layer can also split or crack along creased edges if the coating lacks sufficient flexibility. Such failures expose the brown or grey recycled fibers underneath and diminish the visual appeal of the finished carton.
Scoring Performance
Proper moisture control during board manufacturing remains the primary method for maintaining the flexibility of the surface layer. Adjusting the ratio of latex binder to mineral pigment in the coating formulation can also alter how clay coating integrity behaves under stress. Print runs are less likely to experience cracking when the folding line is properly aligned with the fiber direction of the board.