High Frequency Acoustic Profiling for Multilayer Board Barrier Integrity
Inline high-frequency acoustic profiling measures micro-scale barrier delamination and polymer layer thickness across dynamic paperboard converting webs.
Multilayer Barrier Board
Composite Integrity
Structural paperboard construction requires high-density fibre plies interleaved with functional films to restrict the transmission of gas or moisture. A multilayer barrier board provides this protection through a central core of mechanical pulp surrounded by bleached chemical layers and a chemical coating. Such arrangements ensure the substrate resists oil, grease, and water vapour while maintaining the rigidity necessary for converting operations.
Conversion Performance
Folding properties depend upon the thickness and grammage of individual plies along with the moisture content at the point of scoring. Converters adjust the indentation depth to account for the specific elasticity of the middle plies since these layers bear the primary stress during the bending sequence. If the bonding between layers fails during the folding operation, the internal structural integrity collapses and the seal of the package suffers.
Variations in room humidity during storage modify the internal stress profiles of the fibre matrix and change the force required to create a clean score line.
Permeation Limitation
Oxygen transmission rates establish the primary metric for evaluating the efficacy of the internal films within the substrate stack. These values measure the volume of gas passing through a square metre of material over a duration of twenty-four hours under defined pressure conditions. The selection of thermoplastic polymers or metalised foils dictates the reduction in permeability that the end user achieves compared to untreated paperboard.
Testing protocols demand exposure to controlled humidity and heat to simulate the real-world environment where the material undergoes environmental strain. The material limits the migration of volatile compounds from the contained product to the exterior atmosphere.