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 user 2013-06-23 at 4:04:57 am Views: 115
  • #2115

    The UV revolution

    There’s Yet another revolution going on in the wide-format inkjet production printing arena. It’s more than just the higher speeds, higher resolutions, streamlined workflow and improved productivity we’ve seen over the past five years. Today the digital printing market is undergoing an ultraviolet (UV) revolution.

    The revolution started a few years ago with the advent of flatbed inkjet printers designed primarily as complements or digital alternatives to screen presses. These machines, the majority of which are equipped with UV-curable inks, are becoming increasingly popular in wide-format print production environments of all kinds – not just screen-printing operations – because of the flexibility and productivity they provide. 

    They can print on a wide range of substrates – both rigid and flexible media. The use of UV-curable inks also makes flatbed inkjet printers more environmentally friendly – they do not emit volatile organic compounds (VOCs) thereby reducing the requirement for special ventilation and disposal systems and more easily complying with increasingly onerous environmental regulations in some regions.

    The advantages of UV-curable inks have begun to extend beyond the flatbed printing paradigm. UV-curable inkjet printing is now poised to address roll-fed applications – primarily outdoor advertising, superwide (grand format) printing and high-throughput digital printing. Because of their obvious advantages, it is forecast that over the next few years, the wide-format printing industry will witness multiple introductions of new roll-to-roll printers equipped with UV curable inks. In short, roll-fed printers represent the next step in the UV-curable inks printing revolution.

    This white paper is intended to introduce you to this latest trend in wide-format inkjet production printing. You’ll learn about why UV-curable inks make the difference in both roll-to-roll and flatbed printers – a difference that could result in new business opportunities and increased profits in your wide-format digital printing environment.

    In fact, the majority of the wide-format flatbed inkjet printers on the market today already use UV-curable ink technology. The next step is the implementation of this capability in roll-to-roll printers – a trend that will initially be of particular benefit to print service providers interested in, or currently operating, superwide printers capable of output up to 16 feet (5 meters) wide.

    Lastly, we’ll introduce you to the first roll-fed, high throughput, superwide inkjet production printer to reach the market – the new NUR Expedio 5000.

    As inkjet printing continues to evolve with increased functionality, higher performance, better cost efficiencies, and continuously improving print quality and colour rendering, the interest in UV-curable inkjet printing technology is set to explode. As a wide-format production print service provider you cannot afford to ignore this exciting new technology and the future benefits it can bring to your operation.

    A word about wide-format inkjet production printing
    As wide-format inkjet printing has increased in popularity over the past few years, the breadth of implementations, price points and performance levels has expanded – sometimes leading to confusion about commonly accepted terminology.

    What do we mean in this document when we refer to wide-format inkjet production printing? Wide-format inkjet production printers and the business opportunity they provide are a breed apart. They can be characterised as follows:
    o Designed for robust, production environments where fast turnaround time is a requirement and on-demand printing of short runs ranging from several to one hundred copies is fast becoming the norm
    o Deliver high resolution (up to 720 dpi or better), often employ 8-colour printing (CMYK plus light C, M, Y, K inks) for expanded gamut and vibrancy
    o Operate at speeds up to 150sqm per hour to produce a range of out-of-home advertising materials
    o Available in roll-to-roll, drum-based or sheet-fed/roll-fed flatbed models in a selection of widths ranging from 1.5 metres to 5 metres
    o Accommodate a wide variety of printing substrates, from paper to mesh, to vinyl and textiles – both rigid and flexible substrates
    o Print using solvent-based inks and, increasingly, UV-curable inks for outdoor longevity without further finishing or lamination.

    Today’s range of wide-format inkjet production printers, or grand format printers, as they are sometimes referred to, can open the door to the production of new print applications, new customers, more work from existing customers, higher profit margins – in short, a full suite of profitable new opportunities for your business.

    Why UV-curable inks are the next step
    Ultraviolet (UV) curable inks are nothing new. They have been used for many years in the cable and wire industry. And they’ve also been used for a number of years in a variety of graphic arts printing technologies including flexography, lithography and screen-printing.

    So what exactly are UV-curable inks and how do they differ from the solvent based inks we traditionally associate with wide-format inkjet production printing?

    UV-curable ink formulations are composed primarily of three components: monomers, oligomers and photo-inhibitors. monomers are reactive dilutants with a low molecular weight that create a homogeneous solution and impart the surface charactertistics of the ink. monomers are organic solids. They do not release volatile organic compounds into the air as solvents do. Rather they become a part of the polymer matrix of the ink film.

    Oligomers form the chemical backbone of UV-curable inks and determine the final properties of the cured ink layer applied to a substrate including the ink layer’s flexibility, weather resistance and chemical resistance.

    Photo-inhibitors are the third component of a UV-curable ink formulation and they control the start and completion of the ink curing process. They absorb ultraviolet energy from a light source focused at the print surface that causes the photoinhibitors to fragment into reactive materials. This, in turn, starts a chemical reaction that converts liquid ink into a solid (this process is called polymerisation) that adheres to the printing substrate.

    The primary factor limiting the use of UV-curable inks in the digital printing market has traditionally been the ink viscosity restrictions of continuous inkjet (CIJ) printheads (Source: New Developments in the Commercialization of UV Curable Inkjet Inks, Jeffrey A Klang, PhD and James S. Balcerski, Ph.D, Sartomer Company, Inc., Exton, PA). However, new printheads have been developed over the past five years that accommodate a dramatically wider range of viscosity.

    The latest UV ink formulations offer higher levels of opacity and the ability to cure with a thinner layer of ink. The ever increasing need for speedy turnaround in screen and flatbed printing applications has led to the development of inks with faster cure rates and lower UV exposure requirements. Additional innovations have led to the development of inks with advanced adhesion, elongation, flexibility, and water resistance properties.

    All of this has resulted in the development of UV-curable inks that can be successfully used on both rigid and flexible media. And this, in turn, has led to the development of UV-based printing equipment by several manufacturers of wide-format inkjet printers that use UV-curable inks.

    The advantages of UV-curable inks
    UV-curable inks demonstrate a number of advantages over traditional solvent based ink formulations. These advantages include fast curing and drying, few volatile organic compounds for limited impact on the environment, excellent colour values and shorter production turnaround times.

    o Fast curing: UV-curable inks change from liquid to solid immediately when exposed to a UV light source. Printed output, therefore, dries instantly and can be handled and stacked or cut without the problems traditionally associated with solvent-based inks – longer drying times, ink offsetting and residual solvent leaking into the room or storage area.

    In contrast, solvent-based inks take a longer time to dry, forcing manufacturers of solvent ink-based roll-fed printing systems to build drying systems into their machines (heated platens, rollers or drying units) to accelerate the process. Because the latent heat required to warm thicker substrates like acrylic panels, rigid PVC sheets and display boards is much greater, the drying techniques used in solvent ink-based systems, do not function effectively for some types of media. For this reason, UV curable inks have become the preferred approach in the latest generation of flatbed inkjet printers that are now becoming increasingly popular.

    o Adhesion: UV-curable inks demonstrate superior adhesion to a very wide range of non- absorbent and unprimed printing substrates and good adhesion to absorbent substrates. Untreated media is less expensive than coated substrates, making printing with UV-curable inks potentially more cost-effective. It also means printing systems that are equipped with UV curable inks are more versatile in so far as the range of substrates on which they can print and in turn, the range of printing applications they can address. UV-curable inks expand the potential number of printing applications that can be produced digitally.

    o Fast and productive: With UV-curable inks there’s no worry about ink drying times. This means printing systems equipped with UV-curable inks inherently accommodate fast turnaround times and high levels of productivity.

    o Long print life: Images printed with UV-curable inks can provide outdoor durability for up to two years. In addition, images printed on rigid substrates can be cleaned using strong solvents and cleaners to remove dirt and/or graffiti, giving them a longer useful life. In many cases a lamination requirement can be eliminated, resulting in fewer production steps, increased productivity and lower production costs.

    o Environmentally friendly: As indicated earlier, UV-curable inks contain virtually no volatile organic compounds. They therefore have a minimal impact on the environment and are especially advantageous in areas where regulations to control and reduce solvent ink emissions are becoming increasingly onerous to printing companies.

    o Excellent colour values: There is no such thing as an opaque UV ink. Rather, they range in opacity from very transparent to translucent. The high level of transparency produces a very clean colour gamut making UV curable inks an exceptionally good choice for four- or eight-colour process graphic printing. (Source: "UV Curable Inks: Will They Work for Everyone?" by Mike Ukena, published by Printers’ National Environmental Assistance Center, http://www.pneac.org)

    o Colour consistency: Because UV-curable inks are heated and jetted at a constant temperature and because a UV light source fixes or "cures" them on to the media, fluctuations in working environment and temperature have a minimal effect.

    Lastly, UV-inks also offer several benefits in inkjet printing systems themselves. First, since they cure only in response to UV light, stand times for printheads is practically unlimited. Inks do not dry on the printhead itself. In addition, with no solvent to evaporate, ink composition remains consistent and the inks retain excellent stability in the printhead thereby reducing the need for purging and cleaning cycles. Less maintenance means more time for higher productivity. UV curable inks also contribute to higher reliability and longer printhead life as well as higher quality, more consistent prints from substrate to substrate.

    In short, characteristics like these make UV curable inks an excellent match for wide-format inkjet production printing technology. In addition to their environmental friendliness and instant cure rate, new UV-ink formulations for inkjet printers deliver flexibility and quality while providing excellent durability and high print gloss.

    While the advantages of UV-curable ink technology have found initial, widespread acceptance in wide-format flatbed inkjet presses, it is now clear that roll-to-roll printers can benefit equally from this capability. In fact, UV-curable inks are now poised to take roll-fed inkjet printers into a new era of performance and versatility.

    State of the market and where it’s going
    As with many market forecasts and predictions from multiple firms, the numbers don’t always match. But the message is the same. The market for wide-format printers that use UV-curable inks is ready to take off. Here are examples from several market research and consulting companies that track the printer industry and forecast trends and growth.

    According to the UK-based firm Web Consulting, the sale of digital printing systems that use UV-curable inks will nearly equal that of solvent ink-based printers in 2005. The firm estimates that more than 4,000 ultraviolet wide-format units will be sold during the next four years.

    Norwell, Massachusetts-based CAP Ventures agrees with the enormous growth potential for printers equipped with UV-curable inks, forecasting a compound annual growth rate of 56 per cent in the number of units shipped between 2002 and 2007.

    I.T. Strategies, based in Hanover, Massachusetts, forecasts the flatbed printer market. It predicts that flatbed inkjet printers, the majority of which use UV curable inks, will generate hardware, media and ink revenues of US$614m by 2008, a CAGR of 23 percent over revenues of US$222m in 2003.

    What’s behind these strong growth projections?
    We’ve already examined some of the advantages that UV-curable inks bring to the world of wide-format inkjet production printing. To reiterate, UV-curable inkjet systems provide all of the expected benefits of traditional digital printing systems and more. They make shorter print runs cost effective and each image can be unique or even customised using variable printing techniques. They deliver a streamlined workflow and lower labor costs – especially compared to non-digital printing techniques like screen-printing, but also compared to traditional printing systems that require printing plates. They also deliver fast turnaround times often enabling print service providers to shorten the time from print order to customer delivery.

    Inkjet printing that uses UV-curable inks brings additional advantages compared to other inkjet systems. The most significant is the instant drying, which can occur in 0.2 seconds. Ink curing and drying is independent of the printing speed enabling the development of higher speed printers that can yield faster job turnaround. UV-curable inks are also applicable for more media than water or solvent inks, increasing the range of media – including rigid substrates like glass, acrylics, polycarbonates, paper, box board, textiles, vinyl, polyester, and many more, including less expensive untreated media. The durability of the UV-cured ink can also reduce the need for a lamination step to protect the surface of prints, thereby reducing costs and waste and eliminating a production step that can often be a workflow bottleneck.

    In short, the newest generation of inkjet production printers that are equipped with UV-curable inks give print service providers the tools to develop innovative new applications with which to go after a plethora of new business opportunities. 

    This alone makes the future for UV-curable inkjet printers extraordinary – a future in which today’s production-oriented wide-format print service providers will surely want to participate.

    * Post was edited: 2004-09-17 10:14:00