There is a large potential for wood-fibre based materials such as paper and board to contribute to lightweight structures in many applications, particularly packaging. Fibre-based packaging materials have in general important advantages in comparison to fossil-based plastics regarding biodegradability, recyclability and renewability. An obvious question is then why plastic packaging is not already overtaken by fiber-based alternatives. Which are the key parameters when a brand owner should decide on a packaging for its highly appreciated product?
To answer this, it is necessary to return to the basic functions of a package. Obviously, packaging should protect and transport food and other goods, and reduce waste and preserve products. This definition only includes the technical functions of a package, and, simply put, a package that does not meet these requirements is not a package. With respect to the technical functions, wood-fibre based materials have today advantages and disadvantages compared to fossil-based plastics, and advocates for both types of materials are working hard to improve on their respective weaknesses.
For the brand owner, however, the marketing functions of packages are as important as the technical functions. Individualisation is a crucial criterion for the use of packaging solutions, and, particularly, with respect to design of geometrically advanced structures wood-fibre based materials have traditionally not been as flexible as plastics. Imagine the difficulties encountered when trying to wrap a piece a paper around a football. Yes, shape matters! Therefore, the ability to design and form advanced paperboard structures is a key technology for the success of wood-fibre based packaging. New sustainable packaging concepts are creating a need for paper materials with considerably enhanced properties.
In the last decade, there have been major advancements in the development of geometrically advanced 3D paperboard structures including technological advances of various forming processes; enriched understanding of the importance and influence of process parameters, and new paperboard materials with significantly improved forming properties as illustrated in the figures.
In addition, great progress is also being made in dry-formed cellulose-based packaging. Today, such are not far behind plastic packaging in terms of design possibilities and surface finish, but of course benefiting from being biodegradable and renewable, and also from being attractive for the consumers. The quality today is way beyond the one of, for example, traditional egg boxes.
Synergies obtained by chemical and mechanical modification of fibres, bonds and network structure have made it possible to develop new paper materials with failure strains many times higher than traditional paper and board.
It is important that the development of new wood-fibre based materials is driven by the particular requirements of the forming processes, and not limited to mimicking the properties of traditional plastics used in processes developed for such. Similarly, it is critical that the future development of manufacturing methods for 3D structures also take the particular properties of fibre network materials into account, because in many applications they require new methods. This development is only in its beginning and major progress is expected in the near future.
Sören Östlund, Professor, PhD
KTH Royal Institute of Technology