Related to seal strength, heat resistance, abrasion of printing ink, there is no difference between the 20 and 25 μm foil used for converting.
Burst pressure is increasing with the thickness of the foil. With this push through, force is increasing too. It is difficult to push a hart gelatine capsule through 25 μm foil without denting/pressing the capsule.
Reduction of packaging material – strip pack – CFF – tropical blister
Moisture sensitive products packed in strip pack are as well protected as in CFF. If sealing layer of CFF has to be identical as strip pack, LDPE or HDPE can be used. As sealing layer of lid foil an extrusion coating of LDPE on 20 μm aluminium is used.
Comparison of strip pack and CFF highlights the main points as:
- more packaging material has to be used
- product is in direct contact with sealing roller (hard gelatine capsule can stick on PE) and temperature sensitive products cannot be packed
Calculations to compare size of pack have shown, that with usage of CFF, 30% to 70% reduction is possible, depending on product geometry. If tropical blister is used, further saving is possible. Reduction in size is not identical with saving of cost. But if all points are taken, every example shows savings:
- production time and output
- lower weight
- smaller folding carton
- more blister in shipper
- lower cost for logistics
These calculations come into play if a customer expresses an interest to switch from strip pack to CFF or tropical blister.
Sealing layer of lid foil (push through) for sealing to CFF with polyethylene (LDPE, HDPE, CFF with desiccant) is produced by extrusion coating. To get sufficient adhesion to the aluminium surface a primer (lacquer) is used between aluminium and PE. Because of this sealing, the layer related to lid foil is double in thickness compared with lacquer of 7 g/m2 where double amount of humidity and oxygen is migrating through it into the cavity.
We were able to develop a push through foil with a lacquer in sealing to polyethylene with 5 or 7 g/m2, depending on customer requests. Not only is the cost less, but more importantly, the cross migration is reduced by 50%. This lid foil is on the market already and replacing the material with extruded LDPE.
- Use of CFF with aluminium of 50 μm compared with 45 μm does not have any advantage related toperformance; cost is higher related to area
- Switching of lid foil with 25 μm aluminium to 20 μm provides an advantage related to cost and change time of a reel
- Change from strip pack to CFF can reduce pack size by 30 – 70%
- Lid foil for sealing to polyethylene with a lacquer can replace the currently used lid foil with LDPE extrusion coating. It provides cost advantage and better barrier related to cross diffusion of a CFF blister.
- If barrier layer of thermos-form films are on inner side barrier properties after forming is increased by 11 – 15%.
Dr Erwin Pasbrig has over 35 years of experience in packaging material for pharma and medical devices for product development and application technique with all leading pharmaceutical companies. He has spent 23 years in the Asian Market. Currently he is working and living in India. He has a Masters in Chemistry from the University of Merseburg, Institute of Technology & Chemistry and has completed a PhD in Chemistry in 1979. Since 1983 he has worked in development of packaging materials, mainly for pharmaceutical and medical application. He has more than 15 patents to his name and has received varied awards for innovation. He currently heads Development and Technology for Aluminium based products at ACG films & foils.