Friedrichshafen, Germany — Swiss injection molding machine builder Netstal Group and its partners have designed a package with reduced plastic content for keeping food like yogurt, cheese, ice cream and salads.
The collaboration between eight companies resulted in a round pail with a paper chassis for German packaging manufacturer Spies Kunststoffe GmbH.
Produced with a Netstal Elion 2200-1000 injection molding machine, the pails consist of a polypropylene rim and skeleton with a wall thickness of 0.92 millimeters bonded to a PP-coated cardboard band.
"The cardboard band serves not only as an outer cover but also takes over the protective function of the contents through the coating," Michael Birchler, head of marketing and communications, said in an email.
During production, a pre-printed band of the coated cardboard is inserted into the two cavities of the mold using in-mold-labeling (IML) robotics.
PP is then injected via channels to fill the rim of the bucket and firmly bond it to the cardboard band.
The material also fills the skeleton, which has a wall thickness of 0.92 millimeters in the area of the flow bars and is made in the same injection molding process as the rim with a cycle time of five seconds.
PP is used for the cardboard coating, too, to ensure durability of the contents and tightness. The package also has plastic seams.
With this application, Netstal and its partners created a novel 1.2-liter pail with minimal weight and maximum content of renewable raw materials, Birchler said. The amount of plastic used is reduced and replaced with coated cardboard, he added.
When asked about the recyclability of coated cardboard, Birchler said, "After consultation with the German Recycling Paper + Cardboard Association, even if the product is sent to the carton collection, it is sorted out for thermal recycling. If there is an existing recycling stream for Tetra Paks in a country, the plastic can be separated from the cellulose by remaining in a water bath for a longer period of time."
Tetra Pak, part of Swiss-based Tetra Laval Group, is a food processing, packaging and distribution company for dairy products, beverages, ice cream, cheese, vegetables and pet food. The business is focused on reducing the use of all raw materials and energy during manufacturing and distribution.
In addition to Spies, Netstal partnered with Muller Technology Conthey, Motan Colortronic, EF Cooling, Sabic, Stora Enso and Engelhardt Etikett.
Some of the partners helped automate the process. After a camera check for quality, robots remove the finished pails and stack them on a conveyor belt. The stacks of pails are then packed into boxes by a collaborative boxing robot.
Birchler summed up the automation like this: "There will be the main linear robot for the IML and takeout process followed by a six-axis robot who will process the vision inspection (reject of bad parts if necessary) and stacking of the pails. A cobot will be occupied with boxing of the stacks into provided trollies."
