As the countdown to 2012 drupa begins, participants throughout the flexographic packaging industry are anticipating new technologies and processes that will become available in the near future.
When DuPont introduced the DuPont™ Cyrel® Digital Imager (CDI), the first Cyrel® digital printing plate, and a fully digital prepress workflow at 1995 drupa , it could be argued that this was the single most important innovation in the flexographic process since the introduction of the first Cyrel® photopolymer printing plate in 1974. Just like gravure and offset lithography, flexography could now move away from film-based prepress workflows and implement a distributed digital workflow with a computer-to-plate (CTP) output.
The CTP approach chosen by DuPont was to apply a thin masking layer, referred to as a LAMs layer (Laser Ablation Mask System), directly to the surface of the digital Cyrel® plate during the plate manufacturing process. The LAMs-coated digital Cyrel® plate was then laser imaged in the CDI. Thereafter followed the same exposure and processing steps that were already in place for film-based (analogue) platemaking. This approach ensured uniformity of the LAMs and simplified the subsequent imaging and platemaking process for tradeshops or printers.
Since the LAMs layer was an integral part of the Cyrel® plate, the digital workflow also had the unique benefit of eliminating the need to perform the main UV exposure under vacuum. Plate waste and undue labour due to out-of-contact spots or dust were dramatically reduced. Most important, however, was that a new digital dot resulted from the fact that one could now expose the plate in the presence of oxygen.
The digital dot proved hugely beneficial to flexography. It significantly improved the resolution of graphics and lines. Simultaneously, shadowed areas were improved and the tonal range increased considerably. On the press, the digital plates and sleeves produced cleaner highlights, more open shadows, a lower dot gain and greater processing latitude than their analog predecessors. This was a crucial step forward for flexography quality.
Of equal or, perhaps, for some, of even greater importance was the consistency that digital plates brought to flexography. The uniform imaging of the CDI and the elimination of the variables associated with films and vacuum resulted in remarkably consistent platemaking and a significant performance improvement in the printing process.
Digital and fast - Cyrel® FAST
The introduction of the thermal process Cyrel® FAST platemaking workflow in 2001 brought rapid platemaking to a packaging industry where every minute counts. The quality of digital Cyrel® FAST plates proved to be excellent. The elimination of solvents or the need for a drying step cut plate processing time down to as little as half an hour. Furthermore, the elimination of solvents and lower energy consumption led to significantly lower CO2 emissions by flexographic platemaking.
The ability of the CDI to obtain a higher resolution requires, in turn, higher resolution digital printing plates. DuPont solved this problem by introducing Cyrel® DPR for the solvent process workflow and Cyrel® DFQ for the Cyrel® FAST workflow.
EskoArtworks, the manufacturer of the CDI, also supported efforts to improve quality with the introduction of HD Flexo II. The outstanding detail that can be achieved with 4000 DPI optics and the improved solid ink density enabled by their increased enhanced screening capabilities allows customers to increase quality with their existing workflows.
FlatTop Dot – the solution?
In 2008 DuPont introduced Cyrel® DigiCorr; the modified digital workflow specifically designed for the needs of corrugated cardboard printing. DigiCorr was an exposure unit modification that allowed the main exposure of the digital Cyrel® plates to take place in an inert or oxygen-free atmosphere. This resulted in a hybrid digital dot with flat tops and broad shoulders resembling a plateau, similar to those produced on analog plates. These hybrid dots proved to be ideal for the pressure conditions in the corrugated cardboard sector. It was now possible to incorporate all of the production advantages of a digital workflow and the quality benefits of digital Cyrel® plates. The Cyrel® DigiCorr technology was recognised by the FPPA as the Technical Innovation of the Year in 2010.
The success of the DigiCorr dot and the introduction of the flat-topped dot workflows from other plate manufacturers logically raised the question of the suitability of a flat-topped digital dot outside of the corrugated segment. With this question in mind, DuPont established the Cyrel® XD-program, a comprehensive research project, with the undertaking to determine whether advantages could be achieved through the use of flat-top dots in other application areas of flexography. Over a period of twelve months extensive testing was performed with a variety of combinations of printing plates, printing machines, ink systems and substrates, which failed to demonstrate any consistent advantage for the flat-topped dot versus the conventional digital dot. While some printers saw a benefit, most were of the opinion that the best results came with the conventional digital dot. As you would expect from a process as varied as flexography, there is no single solution that satisfies every need.
Although the flat-topped dot does not appear to offer many consistent benefits outside of the corrugated segment, one of the other attributes of plate exposure in an inert (oxygen-free) environment is the ability to maintain exactly 1:1 reproduction of the information that has been imaged onto the LAMs layer in the underlying plate. Although the inert atmosphere suppresses the natural „dot sharpening” that happens in the presence of oxygen, an advantage that has proven so beneficial in terms of quality and consistency, it does introduce the opportunity to perform „structuring” of the printed surface. The CDI depicts here a pattern with very high resolution in all areas of the solid areas, creating a series of small cells that act to carry more ink on the plate surface. This results in improved uniformity and improved solid ink density on the printed result.
Since there may be specific beneficial applications beyond corrugated, and recognizing the inherent flexibility of the Cyrel® DigiCorr technology DuPont has decided to broaden the range and will be introducing Cyrel® DigiFlow. With this relatively simple and inexpensive modification of the existing line of DuPont imaging units the creation of an inert atmosphere is possible during the main exposure. For this, the printing plate surface is flooded with nitrogen when flat-top dots or the structuring of solids is required. The Cyrel® DigiFlow imaging units are designed for use on an „as required” basis and can easily be switched off when the standard digital dot is the preferred result. Because of the low cost and ready availability of bottled nitrogen and the flexibility of the the Cyrel® DigiFlow, DuPont believes that it is the simplest and most cost-effective solution for those users desiring the ability to seamlessly switch between standard and flat-topped digital dots.
Precisely and productively - Sleeve technology
The cost aspect is becoming more of a critical concern for many users. Increased global competition, the continuing consolidation of the packaging value chain and the recent economic slowdown in some regions – all of these factors have had an impact on the profitability of many companies. This reduction in profitability has caused many printers to put the increase in productivity and a reduction in production costs as their highest priority. For these reasons there has been a wave of investment in for example, high-speed printing machines with sleeve functions.
Brands owners are also trying to cut costs. One measure is the significant reduction of packaging stocks. By reducing inventories, they have less working capital tied up and maintain the option to revise graphics at very short notice. As a result of this focus on minimum inventories, it is not uncommon for the same job to go back to press at least five to ten times.
DuPont™ Cyrel® round and Cyrel® FAST round can satisfy the needs of both the printer and the brand owner. By replacing flat plates with Cyrel® round or Cyrel® FAST round sleeves, printers are able to take full advantage of the automation and quick changeover capabilities of today’s state-of-the-art printing machines. In addition, the excellent calliper uniformity of Cyrel® round and Cyrel® FAST round sleeves means that the machines can run at the highest possible speeds. The result of perfect register and outstanding tone and line work takes flexographic to the next level of quality and productivity.
Cyrel® round and Cyrel® FAST round sleeves also enhance flexography’s competitive position versus gravure printing. The calliper uniformity that enables high press speed also leads to the fact that sleeves can be driven with minimal impression. This gives the sleeves a similarly long life as their corresponding cylinders in gravure printing. In this way, printers can benefit from lower overall production costs of flexography and shorter running time.
DuPont is committed to making a complete sleeve workflow available to all who may benefit. The processing system Cyrel® FAST round was introduced in 2010, and many more installations of this unique system will follow in Europe and North America later this year. In addition to the original European production site, DuPont is in the process of starting up new production sites for Cyrel® round and Cyrel® FAST round sleeves. Finally, DuPont is working closely with key industry players such as EskoArtwork and Inometa to ensure that a complete round digital workflow is fully supported at both prepress and the end-user.
More info:
www.dupont.com