Pilot equipment facilitates nanocellulose development

Hans Henrik Øvrebø, researcher at Borregaard, shows a sample of 10 % MFC paste a product from their production plant.

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Nanocellulose is perhaps not on everyone’s lips but is a widely spread buzz word within our industry. A “googling” on the word nanocellulose while writing this article resulted after a search time of 0.45 seconds in some 701,000 hits. So the topic is obviously a hot one.

A wide range of nanocellulose applications are mentioned in articles and, presentations, on posters and at conferences but how many have materialised on an industrial scale? Only a few and one example is Borregaard’s plant for microfibrillated cellulose, MFC, with the trade name Exilva. It has a capacity of 10,000 tonnes of 10% MFC paste and is claimed to be the world’s first commercial production facility for MFC. There are also a couple of other plants in the world but we are still waiting for the critical mass, i.e. big plants and major applications, to be achieved for nanocellulose based products.

Which are the value chains where nanocellulose will be an important component in products and in which applications will it be used? Judging from existing research projects there are different possible opportunities where nanocellulose can be used in full scale. Certain applications require some kind of paper machine technology in order to materialise and hence there is research aiming at products like filters, foam composites, flame resistant material as well as surface treated material for web production.

Needless to say, producing products like these and similar ones in a web form offers many challenges. Quite many are due to the process as such and as they are solved, and when transferring successful results to full scale production, other ones are likely to show up. So, what can and must be done in order to reduce development costs to bring nanocellulose containing products successfully to the market? An important part of the development work is also to produce demonstration samples of nanocellulose containing products in quantities big enough to facilitate application trials on a realistic scale.

Numerous research projects are going on worldwide and hence there is a growing need for relevant pilot equipment and demonstration plants in order to take successful laboratory results closer to efficient big scale production. Nanocellulose is, as the name clearly indicates, very small parts of cellulose molecules, much smaller than any other raw material used in today’s paper machines. So there is definitely a need for pilot equipment in which the process in a paper machine can be simulated in a reasonably realistic way than can be done in laboratory sheet formers.

A small pilot paper machine is ideal to use in many nanocellulose trials.

Questions to be answered before entering full-scale trials in a real paper machine are e.g.; How should a paper machine be modified for production of nanocellulose containing materials? Which white water chemistry will optimise retention of nanocellulose? What happens with the nanocellulose containing web in the drying section? These and other questions are crucial in particular regarding products in which nanocellulose is a substantial, or perhaps even the major, component. As successful laboratory projects involving nanocellulose are showing interesting opportunities, the need for pilot equipment simulating a paper machine has increased.

One such suitable pilot paper machine is the one run by MoRe Research in Sweden. It has a width of 225 mm, a Fourdrinier wire section, a press section and a drying section. It is also equipped with a Yankee cylinder to facilitate production of tissue as well as MG papers. Papers can be produced in a grammage range from 20 to 300 gsm. Originally it was used for MoDo’s paper and pulp R&D projects as well as to service the pulp customers. Depending on changing development needs the pilot machine has been modified many times over the years. The fact that the pilot paper machine is very flexible, using limited but big enough amounts of nanocellulose for realistic trials, has made it a vital part in more and more nanocellulose projects.

As already indicated the issue of nanocellulose retention for production in a paper machine is crucial. How to make the nanocellulose stay in the product and not being accumulated in the white water system? In multi-layer technology multi-layers of anionic and cationic components are step by step built up on a surface.  Fibres can therefore be treated sequentially with anionic nanocellulose and cationic components. Multi-layer technology is a very interesting technology to “load” new properties to the fibre surface and thus develop new nanocellulose based material and composites.

MoRe’s pilot paper machine has therefore been equipped with special equipment for adding anionic and cationic components in sequence. The size of the machine makes it possible to produce demonstration material of nanocellulose products in amounts big enough for many end-product application trials.

MoRe Research’ pilot equipment is equipped to conduct multi-layer technology trials. Multi-layers of anionic and cationic components are step by step built up on the fibre surface.

As mentioned in the beginning, nanocellulose is an extremely interesting area and much money is invested in research and development of processes and potential applications. My intention with this article is not to provide a complete list of different pilot and demonstration plants existing globally, but with one example stress the necessity of using pilot equipment to bring the nanocellulose development forward to facilitate commercialisation, turning nanocellulose into an important component based on renewable raw material for the future.

Finally, it is quite obvious that nanocellulose will be a development area for many years to come. Different technologies and processes will be tried similar to the situation during the childhood of pulping processes. As time passes some processes will prove more successful and be the dominating ones. An important part on the road forward will be pilot equipment, like the one described above, and demonstration plants before full-scale production nanocellulose containing products have become common.