October 2009 — Dramatic shifts in the retail environment in markets around the world have led to the need for corrugated packaging to function and communicate in ways never previously imaginable. These developments have also led to a degree of merging between the historically segregated corrugated sectors and so-called folding carton segment into an inclusive packaging industry, one that despite always being under pressure from suppliers of alternative packaging materials – has generally retained a large degree of popularity for one reason or another.
Until comparatively recent times the retail environment remained fairly static. Every store had a clerk or clerks, who assisted shoppers with their purchases. The advent of the supermarkets or superstores changed all of this, especially the way in which goods were marketed and displayed. Less reliance was placed on shop assistants or clerks. Instead, self-serving merchandising became the order of the day. A wider product choice and the need for supermarkets to shift goods in larger numbers than ever before to realize a profit and satisfy shareholders meant that a product’s packaging had to act as a silent sales person – vibrant colours, bold graphics and crisp text became essential.
Much of corrugated board and folding carton is now printed flexo either directly onto finished board, pre-printed onto the outer layer or liner or by laminating. Initially the driving force behind flexo was the move to increase speed and combine printing and finishing into a single step, not for reasons of quality. The so-called long-way letterpress printer that had for so many years dominated the industry, using paste inks was uncompetitive in the new fast moving retail age, as the letterpress inks were slow to dry.
Flexo today is of course not only fast but issues surrounding print quality have for the most part been addressed. Nevertheless, defects can and do occur during corrugating which may impact on quality. These defects are associated with flute integrity, caliper, wash-boarding and warped board. Ink formulation, photopolymer plate selection, and anilox and inking system, all of which make a contribution towards final print quality, must be chosen with care if print quality and consistency is to be achieved.
Other factors influencing print quality include print pressure; the pressure that will affect good ink transfer to the linerboard and viscosity profile during the print run, colour matching and ink drying speed, etc.
Applying high quality print directly to corrugated is difficult because of the construction of board. The flutes themselves may cause unevenness of print. In addition, producers would rather not squeeze the substrate between print rollers for risk of deformation of fluting and subsequent reduction of final product strength. For these reasons methods have been developed to pre-print the outermost layer prior to gluing to the fluting in the board machine. The technique of pre-printing liner has revolutionized decorative possibilities; a downside is that manufacturing corrugated with a pre-printed liner for anything other than long runs is expensive.
Another option is to laminate a pre-printed liner, a favoured option when the highest-grade paper is used and where the client demands the highest level of quality. Everyone from the provider of corrugated material to the printer and customer have an interest in brand presentation. Consequently there is a high level of shared goal settings between the various providers in the supply chain, including the printer, the ink maker and other suppliers.
From a manufacturing perspective, the challenges inherent in printing on a combined substrate, most notably the effects of fluting, drove the need for more accommodating substrates, and this led to the introduction of small flutes; E-flute followed by F-flute, G and N. The introduction of smaller flutes permitted better print quality, the introduction of these new flutes also began to blur the line between box making and folding carton.
Poor presentation affects sales and print providers have long accepted the need for systems and equipment that enables users to maintain quality standards when flexo printing. Not only that, with profit margins squeezed printers, converters and others look for competitively priced systems and equipment that contribute to in-plant efficiencies. A number of manufacturers have risen to this challenge and have developed equipment that addresses these problems. Colour communication and print/coat technology specialist RK Print Coat Instruments Ltd is one such company.
The award-winning FlexiProof 100 and FlexiProof UV was devised and developed by RK Print Coat Instruments to enable producers and users of flexo inks to bring process variables and colour matching under control while reducing waste and press downtime. Used across all segments, corrugated and carton associated customers have included Mondi Savoi, JSC Cardboard in the Ukraine and Mondi Kraft in South Africa.
A multi-tasking bench top system, both the FlexiProof 100 and FlexiProof UV are used for the production of customer presentation samples; for determining printability issues such as scuff resistance, durability and gloss, etc. The FlexiProof is used in place of a production press for product trial purposes; as an educational tool, providing trainee operators with essential skills and flexo research centres with the means to advance the flexo process. Most importantly the device enables users to colour match off press, saving on-press material costs. Issues of quality control, for example, evaluating how inks and substrates interact and react over time, are all undertaken on the FlexiProof devices.
Other devices in RK Print Coat Instruments portfolio include the Rotary Koater and VCM (Versatile Converting Machine) – each of these devices provide the purchaser with the means to undertake test, monitoring and quality control tasks – and undertake small-scale production. More than 15 different print head and coating/lamination technologies are available.
For further information email sales@rkprint.com, www.rkprint.com
Source: RK Print Press Release
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