Improving the plastic window patching process in window box packaging, mostly by using plasma surface technology, involves enhancing adhesion between the plastic window film (e.g., PET or PVC) and the paperboard or cardboard substrate. Plasma surface treatment helps by modifying surface energy, allowing better bonding without extra adhesives or with reduced adhesive use.
1. Challenges in Window Patching
- Poor adhesion between plastic and paperboard
- Delamination or peeling over time
- Excess adhesive use leading to mess or warping
- Compatibility of coatings, inks, and substrates
2. Use Plasma Treatment to Modify Surface Energy
Plasma surface treatment increases the surface energy of both the plastic film and the paperboard to improve bonding. This is done by exposing the materials to Atmospheric Plasma discharge.
- Improves adhesion of glue or allows glue-free lamination
- Enhances printability and ink adhesion on plastic films
- Reduces glue consumption and drying times
- Works on recyclable, coated, or difficult materials
- Less adhesive waste, no chemical primers, resulting in lower costs
- Eco-friendly, no VOC emissions vs. solvent-based primers
3. Plasma Treatment Integration in Process
Integration points in the window patching machine:
- Before glue application: Treat the plastic film (e.g., PET, PVC) with plasma just before it is fed to the patching station.
- Dual treatment: Optionally treat both the paperboard window area and the plastic film to maximize bonding.
You can integrate a plasma treater head (typically inline) between the film unwinding and gluing unit.
4. Parameters to Tune in Plasma Treatment
- Power level (W): Must be high enough to modify surface without damaging film
- Treatment speed (m/min): Match to production line
- Gas composition: Air, oxygen, or nitrogen depending on desired surface chemistry
- Treatment width: Ensure full coverage of bonding area
5. Measure and Control Quality
Use dyne level tests or contact angle measurements on the plastic film to verify surface energy post-treatment.
6. Upgrades
- Use of functional coatings: Combine plasma with nano-coatings or primers for more durable bonds
- UV-curable adhesives: Plasma-treated surfaces bond better with UV adhesives
- Recyclable adhesives: Use plasma to support glue-free or compostable window patches
Please contact Keylink Technology if you like assistance in selecting a plasma system based on your production speed and material as well as for plasma integration into an existing window patching line.
