New two-layer concept for lightweight container-board - making the impossible possible

摘要

During the past twenty years fluting and linerboard basis weights have decreased significantly on a global scale. This requires higher containerboard machine speeds to reach the targeted or increased production capacity. This is already evident in the higher design speeds of new installations.rnWhile basis weights have decreased, the use of recycled fibre as the containerboard furnish has increased. Economic pressures require cost reductions, which has led to the use of mixed waste instead of high quality OCC.rnThe market situation today is extremely challenging. Large, new investments are difficult to justify. Raw material and energy savings are one way to improve the situation, but this is seldom sufficient in itself. A new way of thinking is required. This paper introduces a totally new, patented, cost-efficient concept for the production of two-ply lightweight containerboard grades with only one hybrid former. This solution gives excellent top and bottom side layer coverage. All earlier attempts to produce lightweight containerboard with a combination of a two-layer headbox and a hybrid former have been unsuccessful. The new concept combines three unique components: the new two-layer headbox and the new vacuum-assisted forming board design with the well-proven shoe blade hybrid former technology. This hybrid forming concept with layering technology is a viable alternative to the production of premium quality lightweight containerboard grades, bringing the speed up to 1400 m/min. The new two-layer concept is especially suitable for rebuilds. As is widely known, separate fourdrinier forming is typically speed-limited to 1000 m/min. At low rebuild investment level the new concept offers the possibility to produce two-ply lightweight containerboard grades with an existing fourdrinier with higher production speeds. With this new concept, the same machine can produce both two-ply linerboard and fluting grades, and is thus an optimally-sized alternative to gap forming technology. The new concept will open up entirely new horizons.