Extrusion International 3-2020

31 Extrusion International 3/2020 Vetaphone A/S Fabriksvej 11, DK-6000 Kolding, Denmark www.vetaphone.com facture brings a number of variables into the equation. For a start, every polymer has its own starting dyne level – that’s its ability to adhere inks and lacquers. Some ma- terials, like PVC or PA, require very little power to surface treat to the correct dyne level – PE requires a little more power, and PP is notoriously the most difficult to treat. You also need to allow for the additives mixed in with the polymers, because these can significantly affect the level of Corona treatment needed, and the power consumed. With all these considerations, what benefit does Vetaphone technology offer extruders? Rossi: It’s all down to good design, which has been funda- mental to Vetaphone equipment dating back to the be- ginning in the 1950s when the company invented and pi- oneered what has become known as Corona treatment. Two principles stand out: simplicity and high efficiency. By designing and building a unit that is user friendly, Vetaphone makes cleaning and setting easy with its quick-change cartridge system. If you back this up with high-efficiency generators that use the patented Reso- nant Circuit, you have the capability of delivering 96% of input power direct to the electrodes. This reduces the heat level, which is an obvious advantage when you are handling lightweight extruded films. There are other fac- tors such as the refined level of control available through our iCC7 interface – but essentially, simplicity and high ef- ficiency are the main benefits here. We refer to surface treatment as Corona – is there an application for Plasma in this sector? Rossi: Not really – but you need to understand the differ- ence between the two processes to know why. Plasma is not a replacement for Corona – it’s a different way of treating the surface of certain substrates that require a chemical as well as a physical treatment. It has more of an application in specialised offline converting procedures where the chemical structure of the material is very com- plex and requires a very high dyne level that Corona can- not achieve. It requires a controlled environment and the use of different dopant gases – and is significantly more expensive than Corona, so used in specialist situations only. How has the extrusion market changed in recent years? Rossi: It’s changed because the markets it’s supplying have changed. If you go back 20 years, the majority of films being extruded were up to five layers for use in the technical and industrial packaging sectors. Nowadays, with the emphasis more on meeting the ever-growing demands of the food, pharmaceutical and hygiene mar- kets, packaging with up to 13 multi layers are far more common, and the product is required to meet a variety of demands. These include freshness, protection and re- cycling, and pose complex problems for manufacturers. Take the current dramatic situation with the COVID19 pandemic, which is highlighting the vital role that pack- aging plays in our daily lives and welfare. Situations like this drive demand for new technology and future applica- tions that enhance the value of so-called ‘clever’ packag- ing. And, it all starts with extrusion! Plastic packaging seems to be ‘Public Enemy No 1’ right now – what steps is the extrusion market taking to become more environmentally friendly? Rossi: Despite public opinion to the contrary, plastic pack- aging has a very low carbon footprint as far as manu- facturing is concerned. But, mindful of its image, and the need to take its responsibilities seriously, I’d say that there are two ways in which extrusion is helping to ‘go greener’. The first is in downgauging the packaging by using new resins that allow for less volume of plastic to be used. This helps with problems like shelf-life and hygiene where the extrusion of a special material removes the need for several laminated and heterogenous substrates. The second is the way the industry is working to simplify the structure of packaging by using compatible resins to improve recyclability as part of the circular economy. It’s not the manufacture of plastic that is the problem – it’s how it’s disposed of after use that is the real issue. Is this the next big challenge for the industry? Rossi: Yes, no question about it. As we all know, the EU has set very ambitious targets for reducing the produc- tion of plastic and increasing the level of recycling. But it’s very difficult to equate the oxygen barrier demand with the sole use of Polyolefin resins. One solution is to ex- trude bioriented blown films, so-called triple bubble tech- nology, where the orientation of the molecules dramati- cally improves the properties of the standard resins used in general purpose packaging. The oxygen barrier will not be as good as that offered by EVOH or PA, but good enough to replace much of the packaging where they are currently being used. There are no simple solutions, but demand drives R&D and gives birth to new technology – extrusion is no different in that respect. Comparison between 9- and 11-layer blown film