Film & Foil Printability and
convertibility of film & foil C
By Tom Kerchiss, chairman, RK Print Coat Instruments.
ommercial and industrial demands are increasingly placing pressure on converters, printers and the supply chain providers to print onto and convert materials that were at one time thought of as specialist or exotic materials. Many of the material developments of modern times have been film, notably thin flexible materials. Over a third of thin filmic production is destined for flexible packaging applications with tried and tested polyethylene (PE) being one of which many converters will be familiar with. However, there are in excess of one hundred filmic materials commercially available and an increasing number of bio-based materials to contend with the possibility that a converter will be required to handle and process a material or materials outside of their comfort zone is increasingly likely.
Films may be mono or multi-layered and depending upon application and selection may be laminated. Co-joined laminates may be made up of layers that provide stiffness and strength. Materials must be dimensionally stable, heat resistant, possess a low co-efficient of friction, and provide anti-static properties, sealability, printability and convertibility. Lamination and other constructs provide barrier resistance with foil and metallized films and papers playing
an increasingly important role meeting many aesthetic and functional requirements. Bear in mind though that from a converting perspective meeting quality objectives does not always go according to plan. For example, filmic surfaces may seem ultra-smooth but irregularities in manufacturing may increase the incidence of scratches and abrasions. Variation in material calliper affects processes such as coating, laminating and slitting. Areas of high calliper detrimentally affect nip pressure, damaging delicate materials.
Even aluminium foil when used as a combination layer within a lamination can sometimes be tricky and need watching. This is especially the case when the foil is ultra thin and is inclined to be subject to microscopic nicks as it travels at high speed. Metallized film can be abraded or scratched travelling through the laminator.
The ability to be able to come to grips with the various idiosyncrasies of a material or materials that a package printer and converter are required to process is critical. Stand up pouches allow for a visually different and in many instances a more practical approach to packaging food and beverage items with foil and/or metallic materials key components.
Pouches, such as those for flexible packaging could be configured in the following manner: (polyethylene terephthalate) PET/print/adhesive/ metallized PET/adhesive/sealant or PET/print/ adhesive/metallized OPP/sealant. A retort pack on the other hand may be configured in the following manner with an outer PET layer/print, an adhesive coating layer/foil/primer coating and a layer of LDPE (low density polyethylene). PET provides printability and imparts stiffness to the structure. The metallized filmic component serves as an oxygen and moisture barrier. The metallized surface also of course looks aesthetically pleasing and enhances product appeal.
If OPP is substituted then functionality is slightly altered though barrier against moisture and stiffness of structure is still obtained. Pouches can of course be co-extruded structures and a wide range of films/foil/papers may be used in a laminated pouch. A membrane of alu-foil will transform a simple pouch into a product, which behaves very much like an aseptic or sterilizable can. A pouch whether it is a stand up gusseted or a pillow pouch occupies a fraction of the space that a conventional can occupies and is of a lower weight.
With so many materials on the market and with process requirements becoming ever more demanding processors need to be at the top of their game. Pilot coat, print and laminating systems enable users to trial materials and consumables off line and experiment using different coating applicator technologies and, as for example with RK Print Coat Instruments VCML Lab/Pilot Coater choose from different drying methods such as hot air, infrared and UV curing. Other systems such as the VCM custom configured pilot/production coater have found favour with converters and manufacturers engaged in the research and production of solar cells, latent imaging, security, medical disposal products and applications associated with automotive, aerospace and much more. Given the complexities of converting many other coating and colour communication systems are available including the K 303 Multicoater and variants; the Control Coater, Gravure coater, the GR100 and K Printing Proofer….and much more.
20
December 2022 / January 2023
www.convertermag.com
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