Why is rotary Offset claiming its position in flexible packaging?
Web Offset printing entered the flexible packaging industry in the early 2000’s. The technology on film laminates has been confirmed as food safe for more than 15 years already and is gaining momentum in 100% solvent-free printing. It addresses the need for decarbonization of the print industry. And as energy prices are rising disproportionally, offset has a substantially lower energy consumption. Is it justified to conclude that electron beam offset with its high print quality and lowest cost becomes a winner?
There is more than one reason why web offset printing is gaining position in flexible packaging.
What is happening to our once so understandable world?
The global packaging market continues to show phenomenal growth. Though industry forecasts vary, there is consensus that a growth of 15% until 2025 may be expected. This growth is the result of trends for more differentiated packaging variety and fragmentation, smaller family sizes, and more languages. The increasing variety in SKU’s leads increasing pressure on the competitive position of packaging printers who face shortening run lengths and short throughput time till a job can be taken ‘on press’.
Consumers are putting a bigger emphasis on personal health, which leads to a healthier lifestyle, increasing the demand for sustainable and circular packaging solutions. Newly developed packaging materials must contribute to the reduction of environmental pollution by avoiding the use of fossil hydrocarbons like solvents where possible.
An aspect rarely mentioned is the (un)necessity of the use of solvents in printing inks. Solvent-based inks contribute strongly to the emission of Green House Gases. A conservative prediction is that we use around 225 billion m³ globally of Ethyl Acetate, commonly used solvent in printing inks. It is difficult to imagine how much that is. It equals 1,400 Suezmax size mega tankers who can carry 160 million liters each, which equals 5.5 million tanker trucks. Putting in line, that is a total length of 70 million km. This would span the world 2.2 times, every year.
On top of the huge energy use of hot air dryers and incinerators, it illustrates the inconceivable impact of solvent-based printing in terms of VOC and CO2 emission.
Is there a solvent-free sustainable answer with low energy consumption at hand? The simple answer is yes. In fact, it has been proven for over 15 years.
DG-AUXO sleeve offset
One answer to undo the environmental problem of solvents is the sleeve offset technology. Initially developed by Drent Goebel, launched in 2003. Over the years sleeve offset with Electron Beam curing (EB) matured into a robust and economically proven print technology for packaging, offering the highest print quality. Line screening of 200 or 300 LPI comes for free, it is for this reason that printed security documents like banknotes, stamps, passports etc. are exclusively printed in offset.
DG press is the successor of Drent Goebel and started its operations in 2009.
In 2015 the second-generation sleeve offset was developed by DG press, and today, DG press launches its newest 3rd generation web offset press: the DG-AUXO 900.
Sleeve offset in packaging is successful running in over 150 presses worldwide. Most users have multiple press systems, convinced about the combination of economic success, print quality and sustainable advantages, distinguishing themselves for brand owners.
Given the strong increase of energy prices due to the current global geopolitical tension and the economic slump resulting from that, offset technology is adding even more economical value to the packaging printing business.
Offset printing can be used for all common film and foil substrates. Substrates down to 12 microns can be driven in the same register accuracy as a CI flexo at high speeds.
Above all, offset is the only standardized printing process that has an ISO standard. It is very consistent in its repeatability. Color is made in pre-press, not on-press. For this reason, color matching is given by the offset plates and pre-press, not by the ink color in the canister, thus reducing start up. Therefore, offset can be considered as a ‘digital’ process, where machine parameters safeguard color consistency, not the press operator.
Due to its accuracy and consistency, offset is ideal for Extended Color Gamut printing (ECG) with 6 or 7 color process. Especially in the fine vignettes with its micro dots of 10 microns printable to a 1% screen is where offset is unrivalled. It can run the full color spectrum without color changes, ink-wash-ups with its related annual ink spill and hard-cake waste.
Gravure and Flexo cannot, or only at excessive machine costs meet ECG requirements, because dot gain and register position color-to-color are unrivalled in offset.
When printing in ECG with offset, you can combine multiple SKUs in one and the same print run together on one web, still warranting true colors:
Increasing SKU’s lead to shorter runs
Economic benefits are not the only difference in offset. Time to market can be as short as within 1 day as pre-press is mostly done in-house, and plate making is a matter of 20 minutes per job, any new job or plate change can be on-press within an hour after received the new files. The color profile of the job is sent via a CIP interface to the press, each print unit has the preset ink profile already on press. The job can commence without any further operator prep work.
Is offset the Magic bullet?
In short: it comes close! As we are all aware there is no real world in which magic bullets exist. Gravure has excellent strength in metallics inks, flexo has best capabilities of heavy laydown in coating, e.g. in a last down white for reverse printing. For these reasons in most cases offset is configured as a hybrid print process using gravure or flexo decks incorporated in-line to the colors printed in offset.
Just to demonstrate a striking example: the same opacity in EB white requires three times less ink compared to a solvent-based white and a water-based white laydown. The demonstrable costs for an expensive EB flexo coated opacity are lower compared to solvent-based white.
So, the essence of sleeve offset is the joined force of in-line hybrid printing with in-line station decks combining 6 or 7 color ECG printing in offset with gravure and flexo decks. Operational energy consumption on average is 65% lower in contrast to traditional solvent-based printing and no VOC’s or solvents have to be incinerated.
As with any real-world technology, packaging printing in Offset has drawbacks. Printing ‘gapless’ in offset is not possible, as imaging in the round is currently not available in the market. The alternative solution to that is called ‘staggered plate’ where a randomly shaped gap offers a solution to such constraint.
Probably the most dominant hurdle is the initial capital expenditure being relatively high. Nonetheless, it can be demonstrated with verifiable and ‘hard’ calculations that offset is always more cost-effective than solvent-based printing.
The main reason is not only the figurative cheap offset plates of less than €10 apiece, readily imaged and accurately mounted in a minute without tape. Another important reason is that in ECG printing fewer colors are required; so less ink, less cylinder engraving, and less make-ready waste, as all data is retrievable as a setting with consistent color performance.
The second drawback is more human-related. The difficulties gravure printers may encounter when migrating their press operators, pre-press staff and salespeople to offset is frequently experienced. It takes a learning curve to entrust the offset machine pre-press technology and step back from spot colors to a 7 color ECG process. Acknowledgement of the need for a training program to absorb the technology will help to shorten the learning period.
There might be presses that can match offset print performance in certain areas, but it is the unique combination of these areas together that make offset stand out from its competition.
The business case
Apart from its unparalleled sustainable performance, the key factor when deciding on offset is the cost-benefit that comes with the process. Supporting the cost-benefits, a part of the detailed comparing calculation between Rotogravure, CI flexo solvent-based and sleeve offset is demonstrated below. These calculations can be shared in detail for verification purposes.
The business case is based on:
• a 15.000 m² print job at a 250 m/min production speed
• 8 color gravure and flexo, vs 6 color required in offset
• a €2.000.000 high-end gravure and CI flexo press, vs a €4.000.000 EB-offset press
• reverse printed with 35% ink coverage per print unit and 80% last down white coverage
To better understand the cost benefits of each printing technology, we compared the cost benefits based on the length of the print job in the chart below, resulting in:
In this business case, cost/m² and CO2 emission balance are calculated.
Offset printing generates 75% less CO2 and is about 3 Euro cents /m² cheaper, offering supreme quality.
Annual GHG per 40.0000.000 m2 print run for each machine
Even when it comes to larger print jobs, DG-AUXO still performs better than flexo and gravure. Only from print jobs of more than 40.000m² flexo and gravure start closing the gap. Because gravure and flexo both have higher origination and cylinder costs, making it expensive to start, only on larger print jobs the costs start levelling out.
We can say that tomorrow’s sagacious flexible packaging printers will be technologically agile. They must be able to adapt their printing infrastructure in the future to meet fast-changing markets and environmental constraints. It is for these reasons that the leading packaging printers engaged in both gravure and flexo need to look at the new option of offset with EB curing. Can they afford not to look at this?
Can offset dethrone solvent-based ink systems in the printing industry, and effectively decarbonize flexible packaging?
About the author
Rob Schellekens is the sales director of DG press Services. He worked in the offset packaging printing industry since 1993 and managed procurement, sales, and production.
In 2009, he started working for Comexi, Spain, being responsible for the EB technology and initiated the functional design of the CI8 sleeve offset with EB technology.
He was involved in the development of the wet trapping Flexo EB ink system ‘Gelflex.’