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Chemistry and technology in partnership PDF Print E-mail
Written by Niklas Olsson, Global Brand Manager, XSYS Print Solutions, 2007   

Narrow-web print has the capability to vary every aspect of its performance. Niklas Olsson of XSYS Print Solutions examines the need for special ink formulations to deliver the best possible results with this versatile technology.

Narrow-web print is a 'niche' segment of the print industry where there continues to be considerable innovation - in every aspect. It offers an enormous portfolio of opportunities to the buyer who is looking for high-quality aesthetics, easy-to-achieve added value, and special functionalities.

What is narrow-web print?

This very versatile print technology, developed originally for printing and converting self-adhesive roll label stock, is almost infinitely variable. Its construction with in-line finishing and converting, as well as modular print station concept, means that it can print as many colours as you want (just by adding another print station), using any print process you want, or a combination of processes; add hot or cold foiling; add digitally-printed variable information; and of course die-cut, waste strip, and rewind printed reels. The recent introduced press technology is so forgiving that it can print virtually any roll substrate, from self-adhesive papers and films to thick toothpaste tube laminate and shrinkable sleeving film.

Narrow-web inks: the challenge

This capability to vary every aspect of its performance makes narrow-web printing a particular challenge for inks, and since the process's inception, specialist inks have been required to deliver the high print quality required. This has entailed the development of advanced formulations for printing rotary letterpress (the original narrow-web print process), screen process (for exceptional colour depth and opacity, with screened white used extensively on clear films as an opaque base for subsequent overprinting in process colour), water-based flexo, and - today's most popular choice - UV flexo.

The premium print quality, combined with high speeds achievable as well as operation friendliness in UV flexo and UV offset print process are now the focus of narrow-web ink specialists, as packaging print buyers seek to match the capabilities of medium-web and wide-web presses - especially for adapting additional business from wet-glue and cut-and-stack labels, over to narrow web in-line converting.

The different combinations of consumables - anilox rollers, plates etc. in addition to inks - required for the different print processes are also central to the need for special ink formulations for narrow-web, to deliver the best possible results either using one single process, or a combination of processes.

Full-colour printing

In fact, building a printed image from nothing across a rotary press, using multiple processes (some of them non-print-based, like foiling, embossing, die-cutting, and over-lamination), is probably the core challenge that narrow-web inks have to meet. At the heart of that offering is, of course, process printing - 4-colour process, the standard for more than 150 years! - but increasingly, due to the requirement for a broader colour gamut, advanced processes like 7-colour Opaltone and 8-colour Hexachrome are seen in the market, along with additional print stations in combination presses to take account of the need for spot colours etc.

As a process more or less dedicated to the packaging industry, narrow-web inks have to meet many end-use requirements - suitability for use on food packaging, low-odour for cigarette packs etc. - and at the same time deliver the colour consistency, often across a variety of print substrates that a brand manager requires for a high-visibility consumer product.

Brand colour consistency

This is the real challenge for ink makers and brand owners when applications and print methods merge. Brand owners are very possessive and careful about the print rendition of their colours: the colour is often the brand. No one, for example, can think of Cadbury without thinking of purple, or imagine Kit Kat in anything other than post-box red. It is therefore crucial for brand equity that precise colour reproduction is achieved every single time.

For the printer, this can pose problems. Brand owners today demand consistency across a broad range of different labelling or packaging substrates, as well as across different print or imaging methods.

Today's ink formulations

Today, solvent, water and oil-based ink formulations are all used in narrow-web print - but advanced UV-curable inks are now available for all the 'standard' print processes - flexo, letterpress, offset and screen, and with digital, and potentially gravure, print. High-speed UV curing adds another element to the narrow-web converter's portfolio.

UV-curable narrow-web inks, in partnership with today's highly-engineered combination presses, can deliver production speeds that would have been impossible just a few years ago. This makes narrow-web print potentially a serious contender for higher-volume print runs - and, of course, more competitive in price terms with the wider-web processes.

Special effects

But that's not all. Narrow-web inks can deliver the special effects, the 'bells and whistles' that brand owners and retailers love, because of their ability to sell a product off the retail shelf. Metallised inks deliver the proven consumer-appeal of label 'sparkle' - at a fraction of the cost of foiling, or printing on a metallic substrate. Gravure gives the best results here, and this is an area of focus for current research in narrow-web inks.

Other decorative effects are achievable with narrow-web inks. Brand owners can add packaging appeal with inks that change colour with changing temperatures (thermochromic) and changing light (photochromic), or with colour-changing optically-variable inks, which display two different colours, depending on the angle of observation. Other options include glow-in-the-dark phosphorescents, and foil-based, eye-catching holographic patterns.

Security labelling and product authentication

Holograms, of course, are also a key component in security labelling and product authentication - and inks have a major role to play in this arena. The self-adhesive laminate has proved itself an ideal 'carrier' for security devices (offering the ability to add a device above, on, or below the print substrate or in the adhesive layer), and the narrow web process's flexibility means that inks can be used as carriers of covert security devices, in-line, within the parameters of a normal print run. Ink manufacturers today can offer a variety of advanced covert product security solutions. Black IR ink that is only readable by infrared scanners is an option, as are invisible UV and IR fluorescent inks - also responsive only to the appropriate readers; and of course conductive inks are a possible future element in the production of RFID tags. At the leading edge of narrow-web security ink technology are many customer-unique solutions based on nanotechnology.

Other 'functional' inks

These functional, rather than decorative, applications for inks are a key development focus - but they have their roots in long-established specialities such as coin inks - which, when the printed surface is scratched, cause an image to appear; scratch-off inks for promotional scratch cards; and magnetic inks. Where would the world of promotions be without these ink functionalities today?

Inks for shrink

The market for packaged food and beverages is one where we see major growth in the use of shrink sleeves - and here the narrow-web print process, coupled with special inks, offers a new print partnership. Here, the inks have a key role to play. The real value that they can deliver is only visible when a sleeve is shrunk on to the container, without any visible deformation of the final printed image. The dedicated narrow-web 'inks for shrink', which have been developed to deliver the desired result - a sharp, bright, colourful, durable image - need to take account, in their chemistry, of the need to be able to shrink up to 60 per cent without loss of image quality and without cracking or embrittlement. This is a key new market for narrow-web printers, who can now compete in quality terms with offset and gravure for sleeve printing.

The future

Looking forward, the major focus of the narrow-web ink manufacturers will continue to be the packaged food and beverage markets, where meeting food safety requirements is coupled with the need for high-impact on-pack print.

The boundaries of narrow-web ink's capabilities are being continuously pushed back, as the manufacturers refine the chemistry to meet the growing needs both of the packaging buyers and the extremely complex delivery platform involving all the print processes, traditional and modern. Ink is the key consumable in the narrow-web print process, and will continue to be an innovative partner for designers, buyers, and users of packaging.
 
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