Biocomposite is a composite material used to reduce a product’s plastic content by replacing it with renewable and traceable materials, such as wood fibre.
Metsä Fibre aims to create added value with bio-based products and reinforce a resource-efficient circular economy. One of the company’s most recent innovations is a pulp-based cellulose fibre pellet product used in biocomposite production.
“This pulp-based product is an alternative to conventional products made from fossil raw materials. It also gives the materials new properties,” says Katja Salmenkivi, Sales Director at Metsä Fibre.
Like a plastic granule, but pulp
The new product is not a finished biocomposite, but a fibre product that the biocomposite producer can combine in the matrix as they wish. The new product is also not a bulking agent, but a component that has a significant impact on the product’s properties. There is no other innovation like it on the market yet.
“In the current products on the market, fibre is always combined with a specific plastic. This means that it must also be used with the same type of plastic. For example, if fibre is combined with polypropene, it can no longer be combined with polythene,” explains Tuomo Niemi, Senior Development Manager and Project Manager in the Cellulose Fibre Pellets Project at Metsä Fibre.
“We have developed a raw material component with no such restrictions. Our pulp-based cellulose fibre pellets can be mixed with different types of plastic.”
Cellulose fibre pellet is a wood-based product. It is manufactured from wet softwood pulp that is chemicalised, pelletised and dried. The chemical processing increases the fibre’s hydrophobicity to improve its binding capacity with hydrophobic plastic.
Cellulose fibre pellets can be combined with both fossil- and bio-based plastics. If the plastic is biodegradable, the entire biocomposite can be categorised as biodegradable.
The finished product resembles the plastic granules used in injection moulding. The injection moulding technique is a method generally used in the production of plastic products. It melts the plastic granule and injects it with pressure into the mould’s cavities, where it cools down and hardens to the mould’s shape.
“We wanted to create a product that resembles a plastic granule so that it would be easy to use in the compounding process,” says Niemi.
Lighter, stronger and stiffer biocomposites
Cellulose fibre functions as a reinforcement fibre that can improve the strength and stiffness of a plastic material. Thanks to their strength, cellulose fibre can be used in objects that must withstand pressure and stress.
“Cellulose fibre makes up 10–40 per cent of a finished biocomposite product. Most of the strength effects are achieved with a cellulose fibre content of approximately 30 per cent,” says Niemi.
The fibre has a low density, which makes biocomposite lighter than a plastic product. The light weight makes processing and transporting the product easier.
Niemi sees three uses with great potential for the finished product: plastic consumer goods, building products and the car industry. For consumer goods, the most interesting ones are reusable products that could offer wood fibre a new, long-term use.
“In construction, cellulose fibre could be used when building infrastructure, for example. In the car industry, the lightness of biocomposite is a key factor for fuel efficiency, so the industry is particularly interested in solutions that reduce weight,” says Niemi.
Commercialisation of a new product requires insight of the value chain
The technical properties of cellulose fibre pellet, which is in the product development phase, are currently being tested with partners. Launching a new product requires a thorough understanding of the entire value chain.
Legislation sets different requirements for different value chains, which each actor must be able to fulfil. The customer base can also vary between value chains.
“Taking all of this into account requires time and preparation, which is why the commercialisation of the product will happen in 2026 or 2027 at the earliest,” says Salmenkivi.