Mechanical Failure
Structural failure of a protective plastic layer on a paperboard substrate occurs when the shear forces applied during converting exceed the cohesive strength of the polymer. This type of polymer barrier shear rupture typically happens along tight folds or creases where the material experiences intense localized strain. Such damage destroys the integrity of the barrier, rendering the package vulnerable to leaks.
Process Origin
Analysis of the scoring and folding stages reveals how improper crease geometry or excess pressure initiates the failure. In these operations, polymer barrier shear rupture is influenced by the thickness of the coating and the temperature of the board. Cold board is more susceptible to tearing because the polymer is less ductile.
Performance Loss
Loss of the barrier function leads to the immediate migration of liquids or gases through the packaging material. When polymer barrier shear rupture occurs in liquid packaging board, it can cause the liquid to penetrate the paperboard core, leading to a soggy carton and potential failure of the entire package. Converting plants monitor the elongation properties of the polymer to ensure it can withstand the mechanical stress of high speed folder gluers.
This control helps maintain a secure seal that prevents product leakage.
