The unbeatable duo
The unbeatable duo cuts emissions by driving down the energy costs of producing printing ink, a product used in nearly every aspect of our lives. Together, the MacroMedia and the MicroMedia Invicta boost productivity by 175 percent per line and slash energy costs by 50 percent for every ton of ink produced.
Stuart Spear, August 2021
For Bühler to successfully cut energy wastage by half by 2025, radical reductions in energy consumption will need to be achieved in every part of the value chain. For most, the production of printing ink has gone unnoticed when it comes to debates about sustainability. And yet, we are surrounded by it every day. It’s on the food packaging that advertises con tent in bright graphics, the publications that tumble off the printing presses, printing ink and dyes are used in our homes, our offices and on the textiles we wear. It is ubiquitous and Bühler has been looking at how to halve production energy costs with the intro duction of what is described as its “unbeatable duo”, the MacroMedia pre-dispersing unit and the MicroMedia Invicta high-performance bead mill. This wet grinding process is also used for coatings and chemical applications, but the most common usage is in the manufacture of printing ink.
The environmental and cost-saving credentials of the unbeatable duo are impressive. Compared to a standard production process the combination of the MacroMedia and the MicroMedia Invicta result in a 175 percent increase in productivity per line. Energy costs are cut by half for every ton of ink produced, which is translated into savings of 200 kg CO₂e being pumped into the atmosphere. The climate change benefit is that a company producing 5,000 tons of ink, dyes, or chemical coatings each year will save the equivalent of the CO₂ capture of 40,000 trees. “We like to feel that the wet grinding process technology, as a business area in Bühler, is doing its bit and contributing to the overall sustainability targets that we are aiming to reach by 2025,” says Angela Zürrer, Product and Strategic Marketing Manager for Grinding and Dispersing at Bühler.
We like to feel that the wet grinding process technology is doing its bit and contributing to the overall sustainability targets that we are aiming to reach by 2025.
Angela Zürrer,
Product and Strategic Marketing Manager for Grinding and Dispersing at Bühler
Ink is a liquid paste containing pigments. Cyan, magenta, yellow, and black are the workhorse colors in the printing world. More sophisticated printers can have up to eight colors, including light cyan, orange, and grey. Each pigment has a rich history behind it. The earliest inks came from materials found in nature, including secretions of octopi, cuttlefish, squid, or tannin from tree bark and nuts. The most famous is purple, or in the printer’s contemporary lexicon magenta. In antiquity it was made from marine snails and boiled for days. It was the color worn by Roman emperors due to its high production costs. Today the origins of pigments are more prosaic, based on chemistry and often closely guarded industrial secrets between commercial rivals. Pigments arrive at the ink manufacturer in powder form, to be added to liquid mediums comprised of water or solvents, binders, and other additives. It is during this wet grinding process that Bühler’s unbeatable duo solutions take center stage.
According to Zürrer, the aim of the ink manufacturer is to make as fine and consistent an ink as possible from the powdered pigment. “The aim of the whole process is to make the pigments smaller in size and to nicely disperse them in the liquid to ensure high color strength and high gloss so that the food packaging looks nice and you feel a smooth surface when you touch it,” explains Zürrer.
Before Bühler introduced the unbeatable duo, the grinding of pigments was the job of the bead mill only. A bead mill is designed to grind particles down to a micro and nano scale by passing the material several times through a grinding chamber containing beads that are being agitated. The applied forces and size of the beads dictate the fineness of the final product as well as the energy required and the processing time. In the past this was a time-consuming and energy-intensive process as producers were limited in the bead sizes they could use because of varied pre-mix qualities.
The ability of the unbeatable duo to cut energy usage by half comes down to a simple law of physics. The smaller the bead you use in the final milling process, the less mass-specific energy is required to create a quality color dispersion and so the more sustainable the product.
According to Zürrer, the secret of the new Bühler solution is to focus on improving the fine grinding process, and to adopt a more holistic view by taking the premixing step into consideration.
“This is why we call the combination of the two process units working together the unbeatable duo,” explains Zürrer. “The MicroMedia Invicta is at its most efficient when all particles in the pre-mix are approximately the same size. But because you often get bigger agglomerates this is not always possible, so using the MacroMedia for preliminary grinding solves the problem, allowing the Invicta to operate at its full potential.” By having a higher quality pre-mix, it is possible to use smaller beads in the subsequent fine grinding step. The result is better bead activation, distribution and a higher flow that translates into more efficiency and productivity.
With the unbeatable duo, the fine grinding process is not really affected by these fluctuations in particle size because we are using the premix process.
Frank Tabellion,
Director Product Management Grinding and Dispersing at Bühler
Dr Frank Tabellion, Director Process Technology Grinding and Dispersing at Bühler, describes the fine grinding done by the MicroMedia Invicta as the heart of the production process. It is here, Tabellion points out, where most of the benefits arise, namely valuable increases in productivity, reductions in energy consumption, and consequently cuts in CO₂ emissions.
“This part of the process requires 80 percent of the energy demand and is also the most time-consuming step in the whole process and it has the largest impact on overall productivity and energy consumption,” explains Tabellion. “By reducing the bead size we can increase the number of beads in the grinding chamber, which increases the number of milling events and so it becomes a more efficient grinding process.”
Energy savings leading to carbon emission reductions and cost savings are some of the major benefits of this approach. It also addresses another pressing issue impacting ink producers. In recent years printing ink manufacturers have been finding increasingly varied particle sizes in their pigments.
The change has happened over the past 20 years as production costs have been forced down through competition. A key part of pigment production is the drying step. By increasing the temperature and so speeding up the drying process, producers are able to reduce costs. “At higher temperatures, particles that have been generated in the chemical process start to form lumps and sometimes they even come together to create a larger crystal,” he says.
This is a constant challenge in the market. It is a challenge the Bühler pre-dispersing process is helping to resolve by ensuring all the material that goes into the fine grinding process is reduced to a constant and manageable size. “With the unbeatable duo, the fine grinding process is not really affected by these fluctuations in particle size because we are using an advanced pre-dispersing process. This is not really the case with other technologies,” Tabellion explains.
As with other Bühler solutions, digitalization is set to become part of the wet grinding story. The Grinding and Dispersing team is currently working with colleagues from the Bühler food divisions to jointly develop new digital services. “What we do have at the moment in this unbeatable duo is the ability to control the whole process and set parameters from one screen,” says Zürrer. “Through Bühler Insights, machines are being connected to the Cloud facilitating the collection and analysis of data on production parameters to ultimately further increase efficiency and productivity. We can then benefit, for example, from data analytics and have access to predictive maintenance data for the machines.”
The direction of travel is clear. However, for the moment the industry is coming to terms with being able to prepare a consistent pre-mix quality for the fine grinding process: an idea that is benefiting manufacturers in terms of productivity, efficiency, and sustainability. “We believe this technology will shape the landscape for how modern inks and coating are manufactured in the future,” says Tabellion.
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