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Digital Package Printing . . . . . . . . . by Dan Malenke Is there a digital press in your folding carton future? The practice of digital printing has grown in recent years and is now finally showing real potential for folding carton applications. A new dawn is upon us. New digital presses, inks, coating, and finishing systems are on the horizon to capture the hearts and pocketbooks of converters, brand owners, retailers, and consumers. Digital printing offers another dimension to product promotion and sales, redefining traditional supply chains, and introducing a model for fast-turnaround, customized, variable print packaging that is literally “on demand”. To understand this new paradigm, it’s appropriate to describe what digital package printing is and how it has evolved. Offset lithography, flexography, and gravure are the process standards, having dominated the folding carton industry for decades. Offset is a workhorse for the printing of high quality graphics on a variety of substrates. Flexography, also known as flexo, is more common with commodity packaging although its capability has expanded through advancements in press, plate, ink, and pre-press systems for the printing of bright, vivid, multi-color images. Gravure maintains a significant market share for the high volume printing of brewery, detergent, and tobacco packaging, among other items. Offset, flexo, and gravure rely on physical and/or chemical means to transfer images1. Digital printing, however, is an electronic form of imaging where particles of pigment are sprayed, ejected, or drawn to the substrate as directed by pulses of energy. Digital printing appeared in the early ‘90’s with the first electrostatic press from Indigo providing inexpensive short-run color printing first on paper, then to a variety of other materials. Narrow web toner-based and digital ink jet presses with inline die cutting are now common for small format label printing from manufacturers including HP Indigo, Xeikon, Domino, Primera, Epson, Jetrion, OKI, Durst, and Xante. Conventional printing expresses tonal print quality in increments of screen ruling. The term “120 line screen” indicates that there are 120 halftone dots per linear inch. This level of quality is characteristic of conventional flexography with analog image processing for folding cartons. Offset lithography commonly uses 150 line screens and higher screen rulings can be used with the smoothest substrates for offset and rotogravure. High definition flexo is also capable of some higher screen rulings. In digital image processing for conventional printing, halftone dots are constructed of definable image specks known as pixels and the resolution is expressed in dots per inch (dpi) or pixels per inch (ppi). A higher level of dpi produces sharper, rounder dots with higher definition (Illustration 1), even with conventional screen rulings.

Illustration 1: Line Screen vs. DPI Resolution Digital printing, on the other hand, always builds tonal images with tiny droplets of ink corresponding to the individual pixels. Digital printing can be found in the range of 600

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to 2400 dpi. Halftone dots are done away with, as are prescribed screen angles, which can sometimes be challenging with conventional four-color process printing. Digital printing has contributed to folding carton solutions, but hasn’t previously been widely recognized as a primary printing process by restrictions of format, size, volume, and speed. Digital presses were typically 13 inches or smaller in width. These are perfect for labels and short run publishing, but most folding carton applications start around 26 inches wide2. Paperboard for digital printing was largely restricted to lower caliper (10-12 pt.) solid bleached sulfate which has a slightly lower moisture content than other substrates and accommodates digital imaging at reasonable production speeds. The newest digital presses solve these issues with formats as wide as 30 inches, production speeds up to 3,500 sheets per hour, and web speeds up to 100 feet per minute. Some systems may also include inline coating, cutting, and finishing capabilities. Various grades of paperboard can be printed at calipers up to 24 pt. and the print quality is quite impressive. In the current landscape, there are three approaches to digital printing for folding cartons: Electrophotography, Ink Jet, and a form of indirect Ink Jet - Nanography. Electrophotography (EPG) Otherwise known as Xerography or laser printing, this process uses pigmented toners, electrostatically drawn to the substrate. HP Indigo has recently announced several 29.5” format presses specifically for flexible film, paperboard sheets, and web-fed paperboard up to .024”. As many as seven dry toner print stations will accommodate process color, spot colors, opaque white, and colors for extended gamut printing. Another dry toner press that can accommodate large format paperboard is from Jadason Technologies and smaller format presses are manufactured by Xerox, Kodak, Konica Minolta, Ricoh, and MGI. Liquid toners may have some advantages over dry toners since heat isn’t required to fuse the image. Production speeds are quite fast and the print quality rivals that of offset lithography. Leaders in this area include Xeikon, Canon-Oce, and Miyakoshi. Ink Jet Ink jet uses droplets of propelled liquid toner in one of two technologies known as continuous inkjet (CIJ) and drop on demand (DOD). The most mature technology, CIJ directs a microscopic stream of ink through piezoelectric printing heads, electrostatically deflected to the substrate. This process has a diverse market from packaging and document printing to industrial applications for textiles, ceramics, flooring, building materials, printed electronics, and product labeling. Since the stream of ink is continuous, this process doesn’t have issues with plugging or drying in the nozzles.

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DOD ink jet propels only those droplets of ink that are intended to print. Most consumer desktop ink jet printers are, in fact, drop on demand. Wide format presses have employed this kind of ink jet for signage since the 1990’s. High speed ink jet also allows for product coding and personalized printed communications. With drop-on-demand ink jet printing, a process known as “material deposition” makes it possible to build up layers of ink or coating through multiple passes. This technique can simulate an embossed surface and create soft touch textures in an overall pattern or in prescribed areas. Ink jet is just now entering the folding carton industry and has certain advantages over electrophotography. Large format printing is right at home and, unlike existing web offset and flexography, there is an infinitely variable repeat. Breaking technologies are coming in the form of high resolution, high speed print heads, and the use of incredibly efficient nano-inks. Presses are now reaching speeds of 1000 feet per minute and print resolutions have reached 1200 dpi. The leaders in this technology include Kyocera, Delphax, Xante, Colordyne, Memjet, Oce, Toshiba, Fuji, and Epson. Nanography A new digital print technology known as Nanography, was introduced in 2012 by Benny Landa, digital printing innovator and original founder of Indigo. This new process signals a breakthrough in printing inks as well as printing machinery. Nanographic inks are microscopic water bourn droplets containing incredibly efficient pigment particles only tenths of a nanometer in size. Nano pigments absorb more and scatter less light than conventional pigment particles3. The Landa Press uses these inks which are ejected from high speed print heads onto a heated, continuous belt. The water evaporates as the droplets are deposited onto the belt, forming an ultra-thin polymeric film. This film is directly transferred to the substrate. It bonds instantly, forming a tough, rub resistant image. Nanography provides high quality printing on virtually any substrate at relatively low cost. It prints with the thinnest of all ink films - less than half that of offset lithography – so it takes less energy to cure.

Illustration 2: Relative Ink Film Thicknesses The Landa press provides 28” format printing in up to 12,000 sheets per hour for films, paper, and paperboard. The user interface is a massive touch screen spanning the entire length of the press and remote operation can also be accomplished through an internet-linked smart phone or tablet. Nanographic printing will impact traditional print processes as well. Various OEM’s including Heidelberg, Komori, KBA, and MAN Roland, have signed partnership agreements with Landa to integrate the nanographic process into their existing offset presses.

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Hybrid Presses, Cutting, Creasing, and Finishing Are printing presses imaging devices or assembly lines? Arguably, the next generation of package printing presses will follow the lead of platform presses from manufacturers such as Gallus and OMET, with independent printing units that are shaftless, gearless, and servo controlled. Print stations will be moved into any sequence combining the best of flexo, gravure, and nanographic printing for one or two sided imaging. Embossing, metallization, barrier coatings, aqueous overprints, UV film casting, and other UV coating will all be done inline. Inline rotary and reciprocating die cutting is common with folding cartons. Laser die cutting eliminates the need for conventional tooling and can also cut cartons inline, but until now, a gap existed with digital creasing. An interesting new system known as the Highcon Euclid generates digital adhesive creasing rules that, combined with laser cutting, makes it possible to crease and cut folding cartons without traditional die tooling and the associated machinery4. Integrated production software orchestrates the interaction between pre-press, color management, printing, and post-press operations; various inspection systems monitor product quality. The combination of all these technologies brings excitement to the folding carton industry! Digital package printing allows for personalized and customized packaging. It can be used in brand protection, providing overt and covert security features and improved product authentication throughout the supply chain. The market for digital printing is growing rapidly. According to Smithers Pira, digital printing for packaging will be worth nearly $12.2 billion with an annual growth rate of 20.5% from 2011-165. Just as smart phones have revolutionized personal communications, digital printing is finding inroads into more and more packaging solutions. Is there a digital press in your folding carton future? Probably so! REFERENCES

1 Malenke, Daniel G., “A Comparison of Folding Carton Printing Processes”, Zumbiel Packaging White Paper, October, 2010 http://www.zumbiel.com/sites/default/files/Printing%20Processes-WP.pdf 2 Fenton, Howie, “Is the Digital Label Market Growing and Why?”, WhatTheyThink, December 17, 2010, http://whattheythink.com/articles/53720-is-the-digital-label-market-growing-and-why/ 3 Milmo, Sean, “NanoInk May Lead to Gains in Digital”, Ink World, August 2012 http://www.inkworldmagazine.com/articles/2012/08/landas-nanographic-presses-nanoink-may-lead-to-gai 4 Ferrari, Michael, “Digital Cutting and Creasing”, Folding Carton Industry, March/April 2012, http://www.mike-ferrari.com/fcmag-cutcrease-2012-03.pdf 5 SmithersPira, “The Future of Digital Printing for Packaging”, December 2011, http://www.smitherspira.com/future-of-digital-printing-for-packaging-to-2016.aspx