Calculating Counter Die Relief Depth across Laminated Substrate Thickness Variances
Counter die relief depth calculation requires adjusting nominal board caliper for dynamic fiber compression, film stiffness, and moisture regain clearance.
Oriented Polypropylene Lamination
Substrate Construction
Biaxially stretched polypropylene film substrates provide high tensile strength and moisture resistance for flexible packaging structures. Packaging converters use oriented polypropylene lamination to combine printed film webs with paperboard, aluminum foil or sealant films. Molecular orientation during film manufacturing enhances optical clarity, stiffness and water vapor barrier properties compared to unoriented cast films.
Corona treatment increases film surface energy to promote ink adhesion and bonding during subsequent lamination steps. The material construction stops at the final rewinding unit before bag forming or pouch converting operations.
Converting Operation
Continuous web processing applies solventless or water-based adhesives between film and paperboard substrates using high-speed nip rollers. Corona or plasma treating stations boost substrate surface energy to ensure uniform adhesive wetting across the film web. Heated nip rollers apply pressure and temperature to cure adhesive layers and eliminate air entrapment between laminates.
Machine tension controls prevent film stretching or web curling during adhesive application and drying cycles. Solvent-free polyurethane adhesives require controlled ambient temperature and humidity conditions to complete chemical crosslinking inside curing rooms. Laminated webs undergo slit-rewinding into specific reel widths for form-fill-seal packaging equipment.
Barrier Performance
Multi-layer film and paper combinations provide protection against moisture ingress, aroma loss and oxygen transmission in food packaging. Executing oriented polypropylene lamination yields flexible packaging webs that protect sensitive food products from atmospheric degradation.