Chemical Migration Test Protocols for Modified Dispersion Coated Packaging
Chemical migration testing for dispersion coated board requires single-sided extraction cells and post-crease migration proofs to account for score-line breaks.
Pinhole Detection
Imperfection Scanning
Inspection systems locate microscopic voids and discontinuous points in polymer barrier coatings applied to paper and metalized foils. Automated pinhole detection uses electrical spark testing or optical scanning to identify micro-scale breaches in protective layers. The presence of tiny holes compromises shelf life by allowing gas and moisture transport through barrier packaging.
Quality standards specify zero allowable pinholes per unit area for aseptic packaging stocks.
Conductivity Testing
Online electrical testing passes extrusion-coated paperboard across a conductive roller while applying a regulated high-voltage potential. Reliable pinhole detection relies on current flow occurring whenever the sensor head passes over a void or thin spot in the non-conductive polymer layer. Sparks jumping through pinholes trigger electronic counter signals that record defect locations along moving continuous webs.
Optical inspection systems employ high-resolution line-scan cameras combined with intense backlight arrays to detect light transmission through opaque foils and paperboards. System sensitivity controls adjust detection thresholds to identify pinholes down to ten micrometers in diameter without generating false alarms from paper formation density variations. Signal outputs trigger automatic marking or defect logging to reject defective roll sections.
Testing voltage must remain below dielectric breakdown limits to prevent puncturing intact polymer coatings.
Barrier Integrity
Evaluation of barrier continuity confirms that coated substrates meet oxygen and moisture vapor transmission requirements for sensitive food products. Effective pinhole detection prevents field failures caused by pinhole leaks in aseptic cartons and liquid packaging boards. Converting facilities use defect mapping data to optimize extrusion parameters and eliminate web inclusions.
Package shelf-life guarantees depend on maintaining defect-free barrier coatings across total substrate surface area.