Printing of the UV adhesive:
Use the correct flexographic printing plate; the hardness value should range between 65 and 70° Shore A
Use a suitable adhesive tape to fasten the flexographic printing plate to the printing cylinder
Use the correct UV adhesive - see the sections previous
Use a suitable anilox roller with an appropriate volume; the correct coating weight depends on both the substrate and the design.
High coating weight: 120 lines /cm ( approx. 300 lines / inch, 8 cm³/m² = 5.2 BCM)
Medium coating weight: 180 lines / cm ( approx. 440 lines / inch, 6 cm³/m² = 3.9 BCM)
Low coating weight: 220 lines / cm ( approx. 550 lines / inch, 4.5 cm³/m² = 2.6 BCM)
Laminating the cold foil onto the UV adhesive:
The distance between the laminating station and the UV curing unit should be no greater than 1 m. If the distance is greater, premature release, wrinkle or bubble formation can occur, which will negatively impact on the transfer.
Separation of the cold foil carrier
- The release angle should be adjustable. Depending on the material, this release angle can be anywhere between very shallow and very high.
Things to be considered when using cold foils:
- The foil tension must be controlled - a too high tension can lead to wrinkles in the lengthwise direction, a too low tension can result in poor guiding of the foil.
- The speed of cold foil transfer is important. A too low speed can sometimes result in poorer transfer; a too high speed can result in inadequate curing of the UV adhesive.
Selecting the correct substrate: Not all available materials are suitable for use with cold foils. To date it has not been possible to use structured, rough, or highly absorbent materials. Smooth, less absorbent, or plastic materials should therefore generally be selected.