Bobst Group SA
Bobst Group SA
06/15/2021 | News release | Distributed by Public on 06/15/2021 07:25
EVOH-free, Topcoat-free Transparent Solution for Full PE Barrier
15 June 2021
EVOH-free, Topcoat-free Transparent Solution for Full PE Barrier
BOBST, working with its partners including Dow and Zermatt have further developed their mono-material MDO PE high barrier solutions to offer an EVOH-free solution which incorporates the AlOx GEN II process and eliminates the need for a top coat. The result is a high barrier mono-material full PE transparent solution as an alternative to metallized polyester film.
Three Pillars of Sustainability
When looking at global market trends for sustainable flexible packaging, the trends can be grouped into three pillars of sustainability: mono-material polyolefins, compostable, biodegradable & bio-based and paper/fibre-based. Within this article, the focus will be solely on the first pillar of mono-materials in which the main driver is to use polyolefin (PP/PE) based solutions based on a single polymer family to improve recyclability. BOBST has based its definition of a mono-material on the CEFLEX guidelines which state that the packaging structure needs to be compatible with the current mechanical recycling process and contain at least 90% by weight of PE or PP; other components such as adhesives, coatings and inks can have a maximum of 5% by weight each.
Mono-material PE Development
In terms of packaging structures, there are currently two significant mega trends in the market: there is a big push towards packaging simplification (delayering) and an ambition to move from non-recyclable mixed polymer solutions to more recyclable mono-material solutions. Figure 1 illustrates this, on the left is a typical structure based on a multi-material duplex laminate. On the right is an example of a mono-material solution incorporating MDO PE with a special co-extruded EVOH layer added to the skin of the MDO PE to improve the oxygen barrier performance and to provide an improved metal receptive skin for the AlOx deposition to improve the overall barrier performance.
Figure 1
Introducing BOBST oneBARRIER
BOBST oneBARRIER is a full PE high barrier solution which has been designed to maximise the amount of PE in the packaging structure to increase the recyclability whilst also giving a more economical high barrier packaging solution.
The concept behind oneBARRIER was to provide an optimized metal oxide receptive layer via wet dispersion coating where typically thinner layers can be achieved compared to co-extrusion methods. Vacuum deposition provides an extremely thin and efficient barrier layer but performance is dependent on the chemistry of the surface to be coated. Combining these thin and efficient methods of dry vacuum coating and wet dispersion coating together with an optimized base film has resulted in the BOBST oneBARRIER solution.
Figure 2 shows that with oneBARRIER the amount of PE in the structure has been increased to 93%
Figure 2
BOBST oneBARRIER Process Overview
The first stage in the creation of the oneBARRIER solution is the resin production by Dow; a special resin was designed to maximise thermal resistance and coating and deposition reception to achieve the barrier requirements. The film was then produced by one of BOBST's customers Zermatt who used their blown PE line installed in their facility in Spain to produce 12 rolls of MDO PE film.
The reels were then sent to Italy where a primer layer was applied on to the MDO PE film using a VISION D 850 at Bobst Italia's Competence Centre, AlOx deposition using the GEN II process was then applied on an EXPERT K5 in Bobst Manchester's Competence Centre, followed by an adhesive which was applied on the NOVA SX 550. The oneBARRIER process eliminates the need for a top coat to be applied.
Figure 3
AlOx GEN II Barrier Performance
Figure 4 shows the results obtained by applying different primers coded A, B, C and E. Primer C and E didn't give the barrier performance that is required so they won't be taken forward but with both primers A and B combined with AlOx GEN II a barrier performance a WVTR ≈ 2 g/(m² d) and OTR < 1 cm³/(m² d) can be achieved.
Figure 4
Full Laminate: Barrier & Laminate Bond Strength
Looking at figure 5, the barrier performance increases for both WVTR and OTR can be seen throughout all the steps in the process. In summary, the oneBARRIER transparent solution provides a barrier performance equivalent to that of metallized polyester (< 1 cm³/(m² d) & < 1 g/(m² d) and the market requirement in terms of laminate bond strength (2- 3 N/(15mm) is also satisfied.
Figure 5
oneBARRIER for a cost effective EVOH-free solution
oneBARRIER offers a cost effective EVOH-free solution and helps to achieve higher mono-material content to satisfy tightening circular economy legislation. Combined with AlOx GEN II, oneBARRIER delivers a clear, topcoat-free completely colourless high barrier mono-material PE solution for metallized PET replacement (OTR < 1 cm³/(m² d) & WVTR < 1 g/(m² d). The solution is designed for recyclability and provides a reduced carbon footprint operation.
The oneBARRIER integrated solution is available now; please contact your usual sales representative or email for more information:
BOBST would like to thank Dow & Zermatt for their contribution to the film production for this project which was crucial in achieving the overall performance.
Bobst Manchester Ltd, United Kingdom