Transparent plastic-like packing material from birch fibril pulp
VTT Technical Research Centre and Aalto University have developed a method which for the first time enables manufacturing of a wood-based and plastic-like material in large scale. The method enables industrial scale roll-to-roll production of nanofibrillated cellulose film, which is suitable for e.g. food packaging to protect products from spoilage.
Nanofibrillated cellulose typically binds high amounts of water and forms gels with only a few per cent dry matter content. This characteristic has been a bottleneck for industrial-scale manufacture. In most cases, fibril cellulose films are manufactured through pressurised filtering but the gel-like nature of the material makes this route difficult. In addition, the wires and membranes used for filtering may leave a so-called “mark” on the film which has a negative impact on the evenness of the surface.
According to the method developed by VTT and Aalto University nanofibrillated cellulose films are manufactured by evenly coating fibril cellulose on plastic films so that the spreading and adhesion on the surface of the plastic can be controlled. The films are dried in a controlled manner by using a range of existing techniques. Thanks to the management of spreading, adhesion and drying, the films do not shrink and are completely even. The more fibrillated cellulose material is used, the more transparent films can be manufactured.
Several metres of fibril cellulose film have been manufactured with VTT’s pilot-scale device in Espoo. All the phases in the method can be transferred to industrial production processes. The films can be manufactured using devices that already exist in the industry, without the need for any major additional investment.
VTT and Aalto University are applying for a patent for the production technology of NFC film. Trial runs and the related development work are performed at VTT.
The invention was implemented in the Naseva – Tailoring of Nanocellulose Structures for Industrial Applications project by the Finnish Funding Agency for Technology and Innovation (Tekes) that is included in the Finnish Centre for Nanocellulosic Technologies project entity formed by UPM, VTT and Aalto University.
Nanofibrillated cellulose grade used was UPM Fibrilcellulose supplied by UPM.
PHOTO: Nanofibrillated cellulose film
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