RECYCLING OF TETRA PAK ASEPTIC CARTONS
Mario Abreu; Tetra Pak Canada Inc.
Aseptic packages are made of several laminated layers, including paper, aluminum and low-density polyethylene. High amounts of non-wood materials and lack of knowledge on the manufacturing of the package has made recycling aseptic packages an issue for the paper industry. The demand for high-grade fibers for recycling led paper mills to look for alternative solutions. Furthermore, studies on recycling aluminum and low-density polyethylene residuals at plastic recycling mills were held in Brazil and showed great results for both paper mills and plastic recyclers.
2.0 Tetra Pak
Tetra Pak has the ambition to become and remain the world leader in liquid food processing and packaging. We supply both packaging material and processing machines. The amount of packaging material sold by Tetra Pak in 1999 was equivalent to 86 billion packages, of various sizes. And most of the packages sold were suitable for aseptic packaging. Tetra Pak has 18400 employees around the world, at 66 production plants, 70 service centers, 9 machine assembly factories, 12 R&D centers and 78 marketing companies, serving more than 165 countries. Currently there are approximately 8200 packaging machines in operation. The packaging material is laminated from paper, low-density polyethylene and aluminum (aseptic packages) and is sold as rolls. Tetra Pak is one of the largest buyers of paper, processing over 1 million tons of paper worldwide per year. All this paper comes from a few suppliers such as Westvaco, Klabin, Potlatch, Stora-Enso and AssiDoman.
Tetra Pak does not buy paper made from (or with) recycled fibers, due to the possibility of food-contact and the high requirements on stiffness. Almost all the board used in North America, Japan, Korea and Australia comes from bleached sulfate pulp. In South America it is mostly unbleached duplex board from sulfate pulp. Europe, Africa and Asia also use unbleached sulfate pulp, but recently the utilization of a three-layered board, with CTMP, has increased due to promoting stiffness and source reduction at the same time.
Tetra Pak Aseptic cartons are multi-layer polycoated paperboards. The type of paper used depends on the product being packaged, the regional market where it will be sold and the manufacturing conditions. But generally it represents 75% of the total weight of the package. The barriers consist of four or five layers of low-density polyethylene and one very thin layer of aluminum, which accounts for 5% of the total weight. A one-liter package weights only 28 grams, despite having 6 or 7 layers. Temperature is responsible for gathering all of the layers, which means no glue or hot melt is added. Also, because there is absolutely no contact between the paperboard and the liquid inside the package, no kind of wet-strength is ever used. Therefore pulping this material in any conventional pulper at a paper mill is not a difficult job. As long as the package is opened, perforated or shredded, thus contact between the water and the paper layer is provided, the layers will separate due to the centrifugal forces inside the pulper. All Aseptic packages are identified as such, generally on the bottom flaps.