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Studies on composition optimisation showed that the mixing of nanoclays to whey protein-isolate (WPI)-based coating formulations offers an effective strategy to reduce the oxygen permeability of coated polymer films. The scaling up of the various processing stages of these formulations was undertaken to prove their industrial feasibility. The aim was to investigate the effect of various preparation methods at different production scales (pilot- and semi-industrial scale) on the barrier performance and morphological properties of the applied nanocomposites. A nano-enhanced composition was converted into a so-called &ldquo, ready-to-use&rdquo, formulation by means of a solid-state pre-dispersion process using ball-milling. The process yielded a nearly dust-free, free-flowing powder containing agglomerated particles, which can easily be mixed with water. The preparation of a coating formulation using the ready-to-use granules and its upscaling for roll-to-roll converting at pilot- and semi-industrial scale was also successfully implemented. The effects of both the production at various scales and ultrasound treatment on the morphology and barrier performance of the nanocomposites were characterized by transmission electron microscopy, scanning electron microscopy, as well as oxygen permeability measurements. Results have shown that the addition of nanoclays to WPI-based coating formulations ultimately led to significantly reduced oxygen permeabilities to 0.59 cm3, 100 &micro, m&middot, m&minus, 2&middot, d&minus, 1&middot, bar&minus, 1 (barrier improvement factor, BIF of 5.4) and 0.62 cm3, 100 &micro, 1 (BIF of 5.1) in cases of pilot- and semi-industrial-processed coatings, respectively, compared to a reference without nanoclay. In both cases, a similar degree of nanoparticle orientation was achieved. It was concluded that the solid state pre-dispersion of the nanoplatelets during the production of the ready-to-use formulation is the predominant process determining the ultimate degree of nanoparticle orientation and dispersion state.

The requirement for evaluating high performance barrier layers with water vapor transmission rates (WVTR) far below 10−3 g/m2 d has been sparked by the growing application of flexible and organic electronics. While several highly sensitive WVTR-measurement techniques are described in the literature, their accuracy and comparability has not yet been tested. There is an absence of direct comparison of these methods. With a growing body of literature referring to different coating and barrier technologies (often under different testing conditions), it is extremely difficult to gather a coherent picture both of the performance of the materials studied and the permeation measurement methods used. In order to clarify these points we report on independent WVTR measurements of the same batch of a high performance barrier film under two sets of conditions in several laboratories with different state-of the-art methods. These methods also include several calcium test set-ups. The results showed that, while some differences are present, there is a remarkable level of agreement between the measurement methods even prior to harmonization.

Flexible packaging films for highly sensitive products that are to be protected against moisture and oxygen need high barrier materials. In the food and pharmaceutical packaging industries, barrier films, which contain a single inorganic layer on top of a polymeric substrate, provide sufficient barrier. For the protection of more sensitive products, such as vacuum insulation panels, organic photovoltaic cells, or organic light emitting diodes, the barrier films are, however, not sufficient and multilayered structures of alternating inorganic and polymeric layers are required as encapsulation material to ensure sufficient product lifetime. One approach for the production of multilayered structures is the face-to-face lamination of two barrier films via lamination adhesives. Such multilayered structures are usually referred to as multilayered high-barrier laminates. Solvent-free, UV-curable, epoxy-based adhesives are promising candidates for multilayered high-barrier laminates. The adhesives best suited for multilayered high-barrier laminates are those that provide both high laminate bond strength as well as barrier performance. In this paper three different types of such adhesives are discussed in terms of their water vapor barrier and adhesion performance. The effects of the structural differences in the adhesives - chain mobility, crosslink density and surface energy - on the laminate bond strength and barrier performance are investigated. Laminate bond strength tests were performed and failure types and failure locations in the laminates were examined. The results suggest that the intrinsic barrier performance of the adhesive significantly affects the barrier performance of the laminate. On the other hand, the adhesive having the best barrier performance shows a weak adhesion performance. An appropriate adhesive was designed by adjusting the type of the flexibilizer and photoinitiator used in its formulation. This adhesive in combination with a barrier film having an enhanced surface energy shows at the same time a promising laminate bond strength as well as barrier performance.

Metallized films consisting of thin, vacuum-deposited inorganic layers are used for a wide range of packaging applications for foods, pharmaceuticals and other technical purposes. They are made as laminates and consist of a polymeric film (substrate), an inorganic layer, mostly aluminum (Al), and a top layer, laminated to the inorganic layer using a suitable adhesive. One major quality indicator in such flexible packaging materials is the adhesion strength between the inorganic layer and the substrate. In order to measure the adhesion strength of thin Al layers deposited on a substrate, the following procedure is often used: Ethylene acrylic acid (EAA)-films are thermally sealed to the Al layers. In a subsequent peel test, the EAA-film is peeled-off at 180 degrees peel angle, delaminating the Al layer from the substrate. This method shows weaknesses in cases of high bond strength: The sealed EAA-film is elongated or even torn during the measurements, whereby it is difficult to obtain reproducible and repeatable results. In this study two alternative approaches have been tested to overcome the weaknesses of EAA-peel test. One of them is to use thermally sealable polymeric films, such as amorphous poly(ethylene terephthalate) and amorphous polyamide (both having a high mechanical strength), instead of the EAA film. Although the adhesion forces might have been weakened during the heat lamination of these selected films onto the Al surface, a quantitative comparison between the three different types of metallized films (with low, medium and high adhesion strength) is found to be promising by this approach. The other approach is to perform the peel tests with the laminates of the metallized films. The laminates are produced by laminating a low density polyethylene film (PE-LD) on top of the metallized film using an adhesive via a bench lamination process. The laminated PE-LD film in this case replaces the EAA-film. In this approach, the laminate structure is similar to the final product in the end-use. The metal adhesion strength is found to be in good agreement with the strength measured for similar structures produced at pilot scale.