The increasing importance of cellulose in textile and packaging markets
Cellulose offers a renewable alternative to synthetic fibres and plastics. New material properties and production methods provide great opportunities for cellulose-based materials, for example in growing textile and packaging markets.
The growing middle-class population has already increased and further increases the demand for textile fibres. However, the supply for the world’s most popular natural fibre, cotton, has stagnated at 25 million tonnes per year, covering about one-third of the annual consumption of textile fibres. Above all, an increase in cotton production is not ecologically sustainable because of large amounts of water and pesticides needed for irrigation.
Synthetic fibres – most notably polyester – cover more than half of the textile fibre market. It is not likely that the shortage of cotton would be covered by synthetic fibres, because the properties of synthetic fibres are not in line with natural fibres and are produced form crude oil.
The more likely cotton substitutes are artificial fibres, which are classified as man-made fibres based on their manufacturing methods but made from renewable raw materials such as wood and bamboo cellulose. “We believe that the market for cellulose-based textile fibres will grow rapidly in the next few years,” says Markku Leskelä, Vice President for Research and Development at Metsä Board. Markku Leskelä served as the research director at FIBIC when the ACel research program began.
Textile fibre from cellulose
For over one hundred years, textile fibres have been manufactured from wood pulp. These fibres are known as rayon fibres and are divided into, amongst others, viscose and Lyocell fibres according to their manufacturing methods. The regenerated fibres are made by spinning the dissolved cellulose into filaments which are further processed to yarns and textiles.
The increase in production capacity of man-made cellulosic fibres is hampered by the environmental and safety risks associated with the current spinning technologies. However, safe and environmentally friendly manufacturing methods are being developed.
“A safe manufacturing method for high quality fibres could lead to a new growth of man-made cellulose fibre production and bring the entire value chain back to Europe, where it has largely disappeared,” says Kari Kovasin, Development Manager at Metsä Fibre, who chaired the management group of the ACel Research Program.
Thermoformable fibre and composite materials
Opportunities to replace oil-based materials with cellulose have been identified also in the packaging industry. The current practice is to shape the packaging materials by folding the paper board or by thermoforming the plastic sheet into the mould, but it is time to find out how the sheets made of fibres could be moulded similarly as plastics without sacrificing the rigidity of the fibre structure. “Thermoformability of fibre-based materials would provide enormous opportunities for packaging design,” says Leskelä.
Thanks to its strength and light weight, the cellulose fibre is ideal reinforcement material for injection moulded plastics instead of glass fibre. Use of bio-based plastics reinforced with cellulose fibres offers possibilities to produce fully bio-based composite materials with good performance.
World class cellulose expertise
“The fact that renewable raw materials can be produced economically in a large plant from sustainable wood is a very good starting point for developing new materials,” Kovasin says. He believes that application areas that utilize cellulose fibres or the structure of cellulose fibre as such are particularly promising. This requires in-depth knowledge of cellulose fibre; such knowledge that is not needed in traditional paper and board manufacturing.
Kovasin urges for a new kind of organic chemistry competence that helps to understand phenomena related to cellulose and its use in new applications.
“We need to develop a multidisciplinary knowledge platform where long-term basic research and applied research meet”, Leskelä says.