Polymer Structure
Flexible synthetic packaging substrates stretched along orthogonal axes offer high clarity and dimensional stability for lamination to paperboard grades. Extruded polypropylene resin yields bopp film, a thin thermoplastic layer applied to folding cartons and flexible packaging to block moisture transmission. Molecular orientation during manufacturing increases tensile strength while reducing film thickness down to twelve micrometres.
The resulting non-polar surface resists liquid water but requires surface activation prior to printing or adhesive application.
Substrate Lamination
Converting operations join thin synthetic membranes to solid bleached sulfate or folding boxboard using wet or dry bonding adhesives. Surface energy on bopp film must reach at least thirty-eight dynes per centimetre through corona discharge treatment to ensure adequate wet-out of water-based or solventless laminating adhesives. When surface energy drops below this threshold during storage, bond failure occurs along the interface during die-cutting or carton erection.
Tension control during unrolling prevents film stretching that causes curl in the finished paperboard laminate after adhesive curing.
Barrier Constraint
Water vapor resistance remains high across the intact surface, whereas gas permeation for oxygen and aromatic compounds remains substantial unless a specialized barrier coating is added. Elevated temperature exposure causes shrinkage and distorts the underlying paperboard structure.
