By Nick Harvey, Apex International
At the mercy of changing consumer preferences, brand owner demands, industry trends and a whole litany of other factors, the corrugated packaging market has morphed and evolved quite a bit over the past decade. And as outlined in a new Smithers Pira report, The Future of Global Corrugated Packaging to 2021, things show no sign of standing still.
Being in the anilox and glue roll business, and having supported the corrugated industry for the last three decades, Apex stays on the cusp of what’s new and exciting. Here are some of the innovations we’re noticing and paying attention to.
The paper reels used in the manufacture of corrugated board exist in a dry state. During production, moisture is added by the application of starch glue. That moisture needs to be removed, because the finished product needs to also be dry.
But while it may seem like a simple thing to get the glue on the paper, both the doctor roll and glue roll can heavily influence the manufacturing process. If the doctor roll has score lines—which can be created by anything from over impression, to adjusting the dams for accommodating different board widths, to cleaning with the wrong materials—extra and unnecessary glue will be picked up and transferred. If the glue roll has corrosion or chrome flaking, it will apply the glue unevenly. These problems will result in increased starch consumption, an uneven board, and washboarding and warping effects.
The solution is to use rolls that are not only free of scoring and corrosion/chrome flaking concerns, but also actively better the process by improving total indicated runout (TIR)—specifically ceramic doctor rolls and welded, stainless steel glue rolls. A glue set with rolls made from these materials promotes faster speeds, reduced glue consumption, easier cleanup, job repeatability and longer roll life.
Consistent and equal glue transfer is important when discussing board production and also relevant when examining corrugated industry trends:
- The market for E-flutes and micro-flutes, which is growing fast
- A demand for a reduction in starch costs, energy usage and board consumption
- The increasing use of thinner and weaker paper
- The proliferation of short-run orders
The need for an efficient glue set really comes into focus here. The surge in E-flutes and micro-flutes means more flutes per sheet, more starch consumption, more moisture in the board and a need for either slower speeds or a higher drying capacity. Better control of the glue application process is essential to deliver the best and most cost-effective results.
Simply put, board quality is the foundation for corrugated excellence, and that is regardless of which printing process is applied.
Digital & 4-Color Flexo
Pre-print and post-print corrugated’s benefits are already well known—they are established processes, they enable long runs at high speeds and their quality is accepted by the industry—but they are not without their disadvantages—changeover times can be slow, there is excess waste and short-run costs are high.
One of the storylines to come out of drupa 2016 was press manufacturers answering the call for corrugated packaging printed digitally. As we’ve seen in the narrow web market, digital printing has its own benefits. Changeover time is minimal and there is little to no waste, making short runs one of its strengths. That plays into CPCs’ hands, as they look for cost-effective ways to produce small jobs for retailers’ private brands, keep reduced inventories, cater to consumers’ desire for personalized and customized packaging, and go from concept to shelf as quickly as possible.
That’s not to say digital has no drawbacks; in reality, there are quite a few. Being a new print process, it requires a large investment—monetary and manpower—along with a different workflow and path through a plant. It has fixed parameters and no flexibility, meaning value-added coatings are not an option. There are inherent limitations in its Pantone capabilities. Specific to corrugated, the high-quality paper that is necessary is more expensive. And speed is a fraction of what’s possible with flexography.
So, we have discussed the pros and cons of pre-printed, post-printed and digitally printed corrugated, but there is a fourth option: 4-color corrugated. As its name implies, 4-color corrugated builds colors using the familiar cyan, magenta, yellow and black ink set. Think of it as a simplified, user-friendly version of expanded gamut printing.
Why choose 4-color over digital? Because it is based on flexography—an established process—there is no upfront investment or drastic workflow modifications to make. And it enables one of the crucial benefits of flexographically vs. digitally printed boxes: The ability to apply a range of coatings and special effects, like glossed or textured lacquers, inline.
It’s at this point some printers might raise one of four objections:
- “My customer won’t accept 4-color!” Digital is already 4-color, so if they accept that, they will accept this
- “My customer has a strict brand color!” Because we are only talking about four colors, there is still room for one or more spot colors in the press’ other units
- “We have trapping issues!” Trapping issues can be caused by the use of an anti-foam agent, so the solution here is to use an anilox that enables you to remove that additive
- “We have registration issues!” Aside from printing on better board, fading out the edges can trick the human eye and allow for some movement of register
The fact is, on a six- or seven-unit press, a corrugated job run with 4-color flexo can achieve 100 percent of the Pantone book. With four decks occupied by cyan, magenta, yellow and black, and the final unit used for a lacquer, there is room for one or two spot colors—Coca-Cola red, Pampers green, Cadbury purple, etc.
But what about variation in board quality from batch to batch? With digital printing, a primer needs to be applied first. That’s not the case with 4-color flexo. Regardless of whether the board quality is good, just average or even poor, no primer is required.
On the plate front, there are many brands, types and variations to choose from. What is essential is the plate hold a high-resolution; its screen must be a minumum 175 lpi. At that number, we are on the cusp of where the human eye can discern individual dots; past that point, the eye only sees a solid color. As the plate’s lpi drops below that minimum, halftone dots become more visible and optical ink coverage appears grainy and flat.
The Anilox’s Role
When considering what a great anilox needs to bring to the table, three things should come to mind:
- Predictable and consistent ink release. This is essential for color simulation printing
- Reducing or outright eliminating ink aeration. As mentioned previously, this enables the removal of any anti-foam additive in the formulation, which helps in eliminating trapping issues
- Color simulation predictability with replacement rolls. This ensures the design remains valid for color month after month, year after year
Genetic transfer technology, or GTT, is the hallmark of Apex’s aniloxes. It uses a patented, open slalom geometry. Whether we are talking about cell structures like 30-degree, 60-degree or elongated hexagonal, or open structures like trihelical, channellox or positive engraving, there is no comparison. This is not a sales pitch and that is not hyperbole—it is based on science.
There are two key areas of benefit we can qualify with science: Applied forces within the ink transfer, and aeration.
Isaac Newton’s Second Law of Rotation gave us an understanding of how acceleration and rotation cause angular changes. If we visualize how ink transfer plays out with different cell shapes, in both conventional and long cells, some uplift occurs. With GTT, because there is no back wall, uplift is kept to a minimum.
Looking at ink aeration, recall it is possible to compress air, but not liquid. When there is positive pressure within the doctor blade chamber, which is caused by the speed of the anilox rotating, it can lead to a micro-bubble effect and an uneven ink layer. Oftentimes the solution is to add an anti-foam, but this can create trapping issues. Because GTT’s design encourages a smooth transfer of ink, there is no bubbling effect and no need for an anti-foam agent. That leaves an even surface to make contact with the plate.
Can It Be Done?
To recap, in order to utilize 4-color corrugated, we need good registration or creative gripping, predictable and consistent ink transfer, accurate color simulation predictability and a high plate resolution of 175 lpi or more, and reduced ink aeration to enable little or no anti-foam additive use.
Is this all feasible? Can a printer achieve all of these goals? Consider that in 1969—nearly 50 years ago—the U.S. successfully put a man on the moon. Then consider that was done using less technology than what is inside the smartphone sitting in your pocket or on your desk. There is no reason—apart from a lack of focus, failure of innovative thinking or inability of industry technologies to work together that we cannot print 4-color consistently.
About the Author
Nick Harvey is the technical director at Apex. Apex International is the world’s largest anilox and metering roll manufacturer. Based in The Netherlands, it has production facilities on four continents, with 120 sales professionals around the world servicing 8,000 customers.
The post The Corrugated Climate – Where the Industry Is Innovating appeared first on FlexoGlobal Blog.
Source: FlexoGlobal Blog