Tensile Deformation and Multi-layer Film Adaptation Technology for Flexo Flexible Packaging Printing
This technical article analyzes tensile deformation characteristics of BOPP, PET, PE flexible packaging films during high-speed flexo printing, and introduces dynamic tension compensation and corona pretreatment process for thin film packaging printing.
Flexo flexible packaging printing mainly targets various thin plastic film substrates for food daily chemical packaging bags. All polymer films have low surface tension and strong tensile ductility, bringing two core technical difficulties: poor ink adhesion on inert film surface and easy longitudinal stretching leading to register deviation during high-speed continuous printing.
Corona discharge pretreatment is indispensable pre-process for all film flexible packaging printing. Untreated plastic film has surface tension lower than 38mN/m, causing ink peeling and poor adhesion after printing. Standard corona treatment raises film surface tension to 48mN/m to 52mN/m, forming micro rough surface to enhance mechanical bonding force between ink and film substrate.
High Speed Flexo Printing Machine - Stack Flexo Flexo Printing Machine
Dynamic real-time tension compensation solves film stretching registration error. Thin film substrates produce micro elongation under constant traction tension, and the stretching degree accumulates with printing length increase. The servo tension system monitors web elongation in real time and automatically shortens electronic repeat length to offset substrate stretching, keeping longitudinal register error within 0.05mm permanently.
Differentiated ink matching for different flexible packaging films. PE soft film matches low-viscosity water-based flexo ink with strong flexibility to fit film bending without ink cracking. BOPP and PET hard films adopt medium-viscosity ink with high surface hardness to improve friction resistance. All flexible packaging inks need excellent bending resistance to avoid pattern cracking during bag making and folding post-process.
Heat shrinkage control for flexible packaging film after drying. High-temperature drying tunnel will cause thermal shrinkage of thin film, leading to transverse web width reduction. Multi-stage low-temperature cascade drying replaces single high-temperature drying module, ensuring complete ink drying while controlling film thermal shrinkage rate below 1%.
Inline functional coating integration for flexible packaging flexo lines. Modern flexible packaging flexo presses add inline anti-fog coating, anti-static coating and heat-seal coating units after printing process, realizing printing and functional coating one-stop production, simplifying post-process workflow and improving finished packaging comprehensive performance.
