Formable paper-based packaging material

Paper and paperboard are the most widely used packaging materials in the world. Paper and paperboard are recyclable, biodegradable, renewable, sustainable materials with excellent printing quality. This provides certain advantages over the most of the plastic-based packaging materials. Increasing environmental pressure is also one driver for the further growth of paper-based packaging market. However, paper is lacking certain barrier properties and flexibility in terms of package design; i.e. paper packaging appears in rather simple geometrical forms while plastics can be formed to a great number of different shapes. Formability is a complex mechanical property that determines the ease of forming of a material. Improvement of the formability is the key to unlock the way to production of novel paper-based packaging, and to increase its competitiveness over plastics. This work overviews various 3D-forming processes such as deep-drawing, vacuum-forming, and thermoforming, which can be used to form paper-based materials, as well as the requirements for the successful forming that depends on the material i.e. formability. It also addresses the features of 3D-shapes obtained with these processes: quality defects, possible uses, and design possibilities. The recent research advances in the improvement of formability of paper-based materials are also covered. These advances include: development of the highly-extensible paper and the investigation of the deformation behaviour of paper in different 3D-forming processes for better distribution of the loads. An approach combining several methods to improve extensibility of paper was tested at laboratory scale, and it is possible to obtain paper with the elongation of up to 35% in MD, while elongation in CD is around 20%. This approach combines mechanical treatments of fibres, spray addition of carbohydrates, in-plane compaction of paper, and unrestrained drying. These treatments affect structure of fibres, fibre bonding, and network in a synergetic way for the improvement of extensibility. Further, highly-extensible papers were converted in the 3D-shapes using the forming processes with the fixed paper blank.