Flexography in Package Printing

Flexographic printing performance, efficiency, quality, and sustainability continue to improve, says Flexo4All.

During the past 30 years, flexography has been demonstrated to be a printing technology with a very impressive growth in terms of quality and productivity. It passed from low- to high-quality printing and today is widely used for packaging production in different applications: flexible packaging, label and tags, plastic bags, carton board and corrugated, shrink-wrap, etc.

Flexography becomes the standard and today is the main printing technology used in the packaging printing industry in America, as well as in Europe (Central, Western and Eastern). But the technology is not standing still and there are continuous process improvements and innovations that strengthen flexo’s leading packaging printing position. A wide range of industry vendors are taking successful steps to make flexo even more productive, cost effective, sustainable, and printing higher consistent quality. Improvements are seen along the whole production process, from the packaging design to the final product.

Improvements in the platemaking room
In order for the quality of flexo printing to rival other technologies, specially offset, the flexo platemakers (services and printers) can use solutions able to combine high-resolution optics with an exceptional screening output. Devices capable of combining 4,000 dpi HD optics with unique screening technologies deliver the advantage of sharper and more accurate imaging. This combination makes it possible to achieve outstanding print quality with a straightforward plate production process. Just as significant, this technology is very easy to use and there is no longer any need for tweaking or adjustments. Moreover, the rounder dot shape produced thanks to this technology combination, means that they are more stable on press, resulting in longer print runs with the same printing plate—even more than standard digital flexo plates. With longer print runs, the press stops less often for wash-ups, resulting in greater productivity.

HD Flexo also brings significant sustainability benefits as well, as it avoids any manual lamination of the plate. Therefore there is no film to dispose once the plates have been imaged. Moreover, thanks to the use of thermal technology for the processing of the plates, there is no need to use solvents, potentially damaging to the environment. Printers who work with plates generated from HD Flexo typically reduce makeready sheets required to get to acceptable color by 66 percent—resulting in much less waste.

“HD Flexo is a big step in flexo printing,” comments Jef Stoffels, Marketing Manager at EskoArtwork and spokesman for Flexo4All. “It makes life easier for brand owners, print buyers, trade shops and converters. It does not require a significant capital equipment investment as it is just an upgrade of existing and running equipment. Trade shops or converters will benefit from HD Flexo because, with a safe, high-quality process, they can compete with offset or other printing techniques without losing quality or having to adapt prepress specifically for the process.”

Improvements in the press room
Even the printing process is undergoing improvements, thanks to increased levels of quality controls available from some press manufacturers. In the world of flexo, the time taken in setting and adjusting a production run is a key factor when it comes to evaluating productivity. On top of this, returned orders affect the reputation of a company and increase its costs. With these issues in mind, new high-performance quality control systems make it possible to guarantee that 100 percent of the production from a flexo printer meets the quality standards set by the customer, while simultaneously cutting set-up times and reducing waste.

Thanks to the high level technology employed by these quality control systems, a wide range of print defects down to just 3 square mm in size can be detected. When used in carton board application, the sheets containing elements identified as defective are automatically ejected, highlighted, or ignored by the press, according to the settings defined for the detection zone the defects occur in and the level of quality chosen by the operator.

Philippe Kunz, Marketing & Communication Project Manager at Bobst, another Flexo4All core member, comments: “iQ300, the quality control system developed by Bobst, is the essential final filter, verifies the production and ensures that the printing reaches the quality needs of even the most demanding end-users.”

Where flexo beats offset
The cardboard packaging market is undergoing a period of renewed development. This is true in industrial countries, where the standard of living is high, as well as in developing countries, including large Asian countries such as China and India. As a consequence, within the printing and converting industry, investment in innovative technology is going to grow. New alternative solutions to offset printing appear, offering streamlined production processes, excellent qualitative results, and interesting profit outlooks. Flexo printing technology results are particularly convenient when low volumes of production are required, often within a limited expense budget. An example is the pharmaceutical industry, whose large orders include such a range of variations that each project is regarded as a separate order.

In these kind of packaging applications, flexo printing provides a higher level of chromatic balance and color constancy than the average offset. “The best results are obtained by flexo printing with UV ink.” states Paolo Grasso, Area Manager at OMET, again a Flexo4All core member. “Without denying the excellent printing quality of sheetfed offset printing used for luxury packaging, many packaging processes can be transferred to flexo lines with significant monetary and time savings. This concept is breaking into many paper product companies as it provides immediate benefits to those who opt these solutions.”

Flexo benefits on inking edge
The latest developments of polyurethane (PUR) resins have opened up new applications. The successful increase of flexography printing of, for example laminates, is highly correlated to the almost unlimited possibilities of the PUR synthesis. Modern polyurethane resins are synthesized through the complex combination of various intermediates by multi-step reactions. Thus high-molecular, film-forming resins are formed exhibiting excellent adhesion properties, high solubility in alcohol, lowest solvent retention, high blocking and sterilization resistance. Properties of polyurethane resins can be varied in multiple ways by selecting specific intermediates. Tailor-made PUR resins can be manufactured and their characteristics can be adjusted exactly to the respective requirements.

“Over the last years intensive laboratories researches brought polyurethane (PUR)-based color inks to be used in flexo printing opening to this technology new possibilities previously reserved only to gravure printing,” says Thomas Bastian, Marketing Director at Siegwerk. “PUR inks exhibit excellent printing results and can be universally applied to a very wide range of substrates. OPP, pre-treated PET, as well as OPA, barriers films coated with SiOx and AIOx can be printed directly with PUR inks.”

About Flexo4All
Flexo4All is a strategic cooperation which combines worldwide expertise from independent companies—suppliers to the graphic arts and packaging printing industry. Born to be a strategic cooperation and not a commercial joint venture to sell complementary products or services Flexo4All aims at:
• Encouraging networking within the flexo industry to create active cooperation among all partners;
• Connecting the competence of all members to deliver knowledge and added value solutions worldwide;
• Promoting the value of flexography as the best technology to satisfy all printing needs;
• Achieving improved and sustainable service for the flexographic packaging printing industry.