Cardboard that can be stretched into shape

VTT developed the stretchable fiber material as part of a three-year pilot project aimed at developing materials that can replace plastic.  

"There is a lot of excellent research being done in universities and research institutes, which unfortunately often remains on a laboratory scale. For the project, 15 potential substitutes for oil-based products were identified, and a survey was sent to over 30 companies asking which of them would be the most interesting and scalable to an industrial scale," says Christian Salminen, who is the leader of bio-based products at VTT.  

Half a dozen products were selected from the pool and developed on a pilot scale. A stretchable fiber material was one of them.  

“Paper or cardboard usually only stretches 3–6 percent. The best commercial products, such as sack papers, have about XNUMX percent stretch, but that’s not enough to create three-dimensional, permanent shapes. The more the material stretches, the deeper the packaging can be formed from it.” 

For example, the deeper the cold cuts package, the more products it can hold. This could be a potential future application for the cardboard material developed by VTT, which can stretch by up to 30 percent.  

Foam-backed technology for stretch 

Foam-weaving technology was central to the development of the material.  

"Foam stretching gives a more homogeneous structure than water stretching. When the variation in basis weight is small, the force during stretching is distributed more evenly and the material does not tear as easily," says VTT's research group leader. Jarmo Kouko says.  

The formation of the fiber structure can also be facilitated by suitable chemicals, which remain on the surface during foaming - exactly where they are needed.  

The Italian company involved in the project had technology that allowed foam-based material to be mechanically pressed together. LUT University, on the other hand, found a machine for molding plastic that was also suitable for molding stretch cardboard.  

“The material fits directly into existing product packaging lines, which is a huge advantage,” says Kouko.  

Next step 

For food packaging, a moisture and grease-impermeable layer is also needed.  

"A thin plastic layer can be added to the fiber packaging, which would reduce the proportion of plastic compared to current solutions. VTT is also developing bio-based barrier solutions - the next step is to combine these solutions," says Salminen.