Steel tube is taking the forest by storm
Invo Tip is lying in front of me on my table at UMV Coating System’s office in Säffle. The patented dispersion tube is one of two secrets in the company’s coating concept of fossil-free packaging barriers for food packaging, a simple steel tube with a modest soft tip.
Nordic Paper Journal & BioBusiness has experienced a ceremonial moment. Senior Sales Manager Per Emilsson and President Ronnie Andersson are about to press the Send button for UMV’s application for co-financing to Vinnova, in order to ramp up the project. Ownership investments, combined with revenue from sales during the pilot run at the facility and customer contributions, will not cover the development costs. UMV therefore needs to share the risk with Vinnova.
Both of the company’s coating concepts, Invo Tip and Invo Coater, can dispense and apply extremely thin coating layers with fossil-free barriers that each give good coverage of the paper’s surface. UMV has applied layers as thin as 1 gm/m2, with sustained high quality. The porous structure disappears with the coating of super-thin layers and the bulky and energy-intensive drying process can be reduced.
During a pilot run, up to six thin coating layers were applied to the paper in the pilot machine to see the properties of each layer, well-aware that paper and cardboard mills usually do the opposite – apply one thick layer.
“The results were striking. The coverage was extremely effective. The actual coater, Invo Coater, applies the coating treatment differently. An upward slit squeezes out barrier coating, which is then dispensed by the Invo Tip element and the overflow is collected in a tray. This takes place at a normal production rate, which can be up to 1 000 meters per minute for a modern board machine. The application and dispensing of barrier coating occurs simultaneously, and the medium applied to the surface stays in place and provides more effective coverage.
According to Per Emilsson, however, the savings potential is not limited to the drying section of the paper machines. According to the concept, a two-step investment in a normal-sized board machine would be in the order of EUR 3-6 million.
“A consolidation of the manufacturing processes in mills could reduce production costs. By moving one processing stage, such as plastic coating, to an earlier production process in the paper machine, one stage of the conversion could be eliminated and significantly increase product value for the mills.
There is no clearly competitive process to UMV’s concept for fossil-free coating with cellulose, protein-based or starch-based coatings. The most advanced processes for coating food packaging apply a large amount of liquid that requires slow and prolonged drying, which requires a much higher investment than UMV’s concept.
A new law is under debate in Germany which may ban return-fiber-based food packaging, due to reports that mineral oils can leach into the packaged food. The oils come from the printing ink in the recycling process. If the law is introduced, many board producers may be forced to quickly adapt their manufacturing methods and either use fresh pulp or apply a protective barrier to the board.
Time is running out and Europe is taking the mineral oil issue seriously.
Mayr Melnhof, an Austrian paper and packaging manufacturer, is preparing to meet the expected requirements and has invested EUR 50 million in curtain coating for barrier coating on the BM3 board machine in its Frohnleiten mill, which produces coated board for food. According to reports, the machine has recently been rolled out.
A wide range of biodegradable polymers such as proteins, starch, cellulose and hemicellulose have been successfully tested at laboratory scale. In general, they have exhibited good barrier properties.
But which barriers provide the best properties – conventional, fossil-based or fossil-free?
The polyvinyl alcohol-based barriers are water soluble and can be re-used, unlike PE coatings. They have probably given the best results to date. Starch is also an excellent barrier but is brittle and cracks if plasticizers are not added correctly. But if they are added correctly, starch can provide a flexible and renewable barrier layer.
“If you want an effective barrier that is oxygen-resistant, you could try fossil-free first, such as starch or hemicellulose, and then use latex as a liquid barrier over the top. You will at least reduce the environmental impact,” says Per Emilsson.
Mikael Hedlund