EXCEVAL™ – Frequently asked questions
- How to dissolve EXCEVAL™?
- Storage of EXCEVAL™ solutions!
- How can possible foaming of EXCEVAL ™ solutions be prevented during solving and application?
- What total solid content can I prepare?
- At what temperature do I need to dry?
- How much material is required to achieve a high gas barrier level?
- How do I improve the barrier properties?
- How to improve the water resistance?
- Can I print on EXCEVAL™?
- Does torsion affect barrier performance?
- How can I increase the coat weight?
How to dissolve EXCEVAL™?
EXCEVAL™ should be dispersed in cold water and then be heated to 95°C inner temperature and kept there for 2 hours. The solution should then be cooled down slowly.
Storage of EXCEVAL™ solutions!
Upon storage at low temperature an EXCEVAL™ solution may gel. Storage at elevated temperature as well as addition of isopropanol (IPA) will reduce the gelling tendency.
How can possible foaming of EXCEVAL™ solutions be prevented during solving and application?
Adding 10% isopropanol to Exceval will considerably reduce the foam formation in the dissolving vessel. The subsequent addition of IPA reduces the foam formation on the gravure rolls. IPA will also significantly improve the wetting of EXCEVAL™ on the plastic substrate. Furthermore, reducing the viscosity of the EXCEVAL™ solution contributes to a reduction of the foam formation on the gravure rolls.
What total solid content can I prepare?
Typically a 10-15% solution should be made.
At what temperature do I need to dry?
No specific temperature is needed as EXCEVAL™ solutions are forming a film upon drying. In contrast, PVDC needs elevated temperatures to enable particles coalescing to form a film.
How much material is required to achieve a high gas barrier level?
A dry weight of 1-2μm is enough to achieve a high gas barrier level (permeation less than 1 cm³·m¯²·day¯¹·atm¯¹).
How do I improve the barrier properties?
Crystallisation is the driving force behind the barrier performance of EXCEVAL™. Any temperature treatment will improve the barrier performance. Storage of the coated film at elevated temperatures (50°C for several days) will allow the improvement of the gas barrier level.
How to improve the water resistance?
Crosslinking will improve the water resistance; however, the crosslinking ratio will reduce the barrier performance. A metal binding complex is preferred in order to combine good water resistance while maintaining the excellent barrier level.
Can I print on EXCEVAL™?
Yes, it has a very good affinity printing inks.
Does torsion affect barrier performance?
To estimate the flexibility of the packaging film, the barrier properties are evaluated before and after mechanical torsion (Gelbo Flex test). Even after 20 torsions EXCEVAL™ barriers demonstrate outstanding performance.
How can I increase the coat weight?
Increasing the coating temperature will reduce the viscosity. Depending on the coating temperature the total solid content can be adjusted. By increasing the solid content the drying time can be reduced.