April 6, 2009 — “Few materials are subject to so many misunderstandings and prejudices than aluminium foil,” says Tom Kerchiss of colour communication and print/coat technology specialist RK Print Coat Instruments Ltd.
From a raw material perspective, aluminium, in its raw state, bauxite, is exceptional in that it is one of the most common materials on the planet. Subject to some controversy, environmentalists say that because the manufacture of even a single tonne of aluminium may involve upwards of 17,500 W/h electrical energy – converting bauxite into aluminium through the melt-electrolysis process is environmentally wasteful and damaging. However, foil advocates counter by saying that this is more than offset by the fact that the material (especially when used in packaging) is made both lightweight and thin. A case of ‘a little going a long way.’ It is also combustible and as a household waste contributes to the possibilities to recover thermal energy from an incineration process.
When it comes to packaging, alu-foil is often used as part of a laminate and is produced generally in widths of 2 metres and then rolled out to thicknesses of as little as 6 microns. Foil used in beverage packaging most commonly has a thickness of 6.65 microns, which produced in widths of 2 metres x 100 gives 55m2 of packaging, or approximately 666 litre packs of fruit juice.
Tom Kerchiss says that barrier properties of foil are superior to all other flexible packaging materials. “Even the sheerest of foil when used in combination with plastic film makes the film impervious to liquids, gases and light.”
In situations where a material that provides the shimmering look of foil but not the barrier resistance is required a metallised plastic film can be used. In this instance the metal is heated to melting point in a vacuum chamber (vacuum metallising process) is which passes a plastic filmic web; metal vapour condenses on the web depositing an ultra-thin layer (0.00002 up to 0.00005mm) of metal to provide the desired metal sheen.
The radiance of foil and metallised papers, etc, has long been recognised by brand owners and marketers as a means of conveying prestige and quality, attracting the consumer and influencing purchasing decisions, hence their importance in product areas such as confectionery, cakes and biscuits.
Packaging converters sometimes print reels of pre-metallised materials such as PP in single ply on flexo or gravure presses. An alternative option is to laminate metallised OPP to another film prior to printing. Tom Kerchiss points out that with a substrate such as polyester the tendency is to laminate to the backing film prior to printing, though sometimes metallised polyester is reverse printed prior to laminating.
In quality focussed markets top-flight printers and converters must produce print jobs to a consistently high standards. In order to minimise the risk of customer returns, and maintain output at the highest level, it is necessary that quality control procedures be in place. This is true whether the material to be processed is foil, metallised papers, film, or something else. However, when it comes to foils, metallised papers and film, quality control is especially important as the brilliance of the surface magnifies surface blemishes and colour inconsistencies.
RK Print Coat Instruments specialises in the manufacture of equipment used to produce repeatable samples of most surface coatings. These may then be used for quality control and presentation purposes, research and development and computer colour matching data, etc. The award-winning FlexiProof 100 and FlexiProof UV enable users to simulate flexo printing for all pre-press applications including quality control and printability testing.
The FlexiProof is a compact bench top scaled down version of a flexo production press. It utilises a doctored ceramic anilox roller and a photopolymer plate. With a maximum speed of 100 metres per minute, realistic printability testing can be performed on all types of flexo substrates. Tests such as wear resistance, scratch resistance, flexibility, gloss and other performance parameters can be undertaken with ease on the FlexiProof- similarly products can be trialled (pilot runs). Trialling a product on the FlexiProof makes economic sense, freeing the production press up for income generating business.
In addition to the FlexiProof, the portfolio of systems available from RK also includes the K Printing Proofer for flexo, gravure and gravure-offset, and for wet/dry laminating purposes, as well as more complex systems such as the Rotary Koater and VCM (Versatile Converting Machine). All units offer a quick return on capital outlay, are easy to use and offer a high degree of accuracy.
For further information email sales@rkprint.com, www.rkprint.com
Source: RK Print Press Release
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