For more than half a century, textile technologists have explored the possibilities of blending different fibres together to maximise fabric performance properties.

By far the most common in apparel today are blends of cotton and polyester – a natural and synthetic combination that has provided the route to maximised economies in achieving a wide range of desirable properties. Only a small percentage of elastane needs to be added to achieve all the stretch wanted in a garment.

Nylon comes into its own in blends when toughness and abrasion resistance are necessary, while at the extreme end of high performance are fibres such as aramids and UHWMPEs (ultra-high weight molecular polyethylenes) which are widely employed in workwear and first responder uniforms.

Man-made cellulosic fibres such as viscose and lyocell have also gained increasing market share in recent years as a more sustainable alternative to both cotton and/or polyester in a range of blends.

Now, however, there is a new game in town – incorporating as much recycled content, preferably from post-consumer waste, as is possible into fibre blends to meet upcoming legislation which will be introduced to set targets for recycling not only in Europe, but also soon in the US and China too.

Spinning

Accommodating recycled fibres is currently not an easy task in conventional spinning, as was outlined at the recent ITMA 2023 exhibition in Milan by Rieter and Saurer, two leaders in automatic spinning technologies both headquartered in Switzerland.

Franziska Hafeli, head of marketing and systems for Rieter said that many of the company’s customers have processed their own pre-consumer yarn waste for decades on Rieter R37 or R70 rotor machines.

“Many of these spinners have not even claimed to be using this recycled material and have included it purely for making raw material cost savings,” Hafli said. “Rotor spinning is best suited for processing yarns with a high short-fibre content but there is also now an increasing demand for recycled ring yarns which need a higher tenacity to go into weaving, but fibre counts for soft touch fabrics are the goal. This, however, is very difficult due to the neps and high short fibre content.”

Short Fibres

Virgin cotton, she explained, has an average short-fibre content of 24.6 per cent, but short-fibre content in recycled pre-consumer yarn waste has an average short fibre content of 46.9 per cent, which makes turning it into new yarns challenging.

This problem is considerably greater when it comes to post-consumer waste, even if it is comparatively pure, she added.

A batch of fibres from recycled white 100 per cent cotton T-shirts, for example, will have an average short-fibre content of 71.3 per cent, with an average fibre length of just 9.8 mm.

Post-consumer waste of such purity is currently rare, and it is for this reason that the accurate and highly automated sorting of waste garments has been identified as a major bottleneck in accelerating the recycling of textiles.

Nevertheless, during the ITMA show, Rieter unveiled a high-quality Ne 30 compact yarn that contains an impressive 40 per cent recycled post-industrial fabric waste.

This has been achieved in a partnership with Spanish fibre recycling specialist Recover and Portuguese spinner and textile manufacturer Polopique.

Extreme Recycling

Today only between 30-35 per cent of textiles are collected separately, but by 2030 the aim in Europe is that up to 80 per cent will be recycled in some way and that the share of fibre-to-fibre recycling will grow to 18-26 per cent, according to Saurer’s chief operating officer Marcus Rennekamp.

“A high degree of contamination, lower production speeds and a lot of personnel intervention are all common consequences of using recycled short-staple fibres in a rotor spinning mill,” he said. “Extreme recycling is the new challenge for yarn producers, with ultra-short fibres bringing conventional spinning machines to their limits.”

Fully automatic rotor spinning essentially consists of four key processes – spinning, winding, automatic piecing (splicing) and the automatic doffing (removal and replacement) of yarn packages, or bobbins.

On the Saurer Autocoro spinning machine, the first three processes have been integrated into each individual spinning position through individual drive technology and the new doffing cleaning units (DCUs) on the Autocoro 10 system have been designed to help spinners to achieve both higher yarn quality and personnel efficiency.

Clean Rotors

When doffing a package, rotor cleaning is carried out simultaneously by the DCUs which travel from spinning position to spinning position. Up to eight DCUs can be configured differently on Autocoro machines, depending on the machine length, package size, yarn count and raw material.

Each DCU can be precisely adjusted to the quality requirements of its lots and work areas and the most important task in the context of yarn quality assurance is to clean the rotors, both pneumatically and mechanically. On the Autocoro 10, this is now even more efficient, with cleaning processes digitally controlled using the latest linear motor technology. A new movement mode for the cleaning scraper has been integrated, and its positioning in the rotor groove is more precise and significantly more efficient thanks to an additional circuit.

Patented

This new cleaning technology loosens and removes even the most stubborn dirt and sticky residue in the rotor to leave them impeccably clean and leading to a more reproducible yarn quality, regardless of the fibre type.

During market launch tests, the cleaning technology proved effective for all fibres that are difficult to spin, including recycled and regenerated types.

A patent on the DCU has now been granted and the new rotor cleaning system will be integrated into all newly delivered Autocoro 10 systems, as well as being made available for retrofitting to older machines.

“We have achieved an energy consumption reduction of 38 per cent on Autocoro systems over the past decade and we are now responding to the latest challenge of the five million tons of recycled fibres that will need to be accommodated by spinners in the next five years,” Rennekamp said.

Saurer sold more than a million spindles on deliveries of its Autocoro spinning units in 2022.

Scandinavian Momentum

There has been a notable response to the challenge of fibre regeneration and recycling in Scandinavia, spearheaded by new companies such as, among others, Infinited Fiber Company, Renewcell and Spinnova.

These companies are all developing not only new pulp feedstock variants for spinnable new cellulosic fibres from waste, but establishing unprecedented new business models and circular supply chains that will ensure their success.

While viscose and lyocell are generally based on wood as a readily available and sustainable feedstock (depending on the sourcing and fibre processing techniques being applied), capacities are now poised to grow with the incorporation of the new pulp feedstocks being developed in Scandinavia.

The top ten producers of viscose and lyocell fibres accounted for 92 per cent of the global market of 6.8 million tons in 2022, according to a report by UK analyst Hawkins Wright, led by Sateri, with global capacity of 1.7 million tons, Lenzing with 1.1 million tons and Aditya Birla with just over 1 million tons. The remaining seven producers are all based in China – Zhongtai Chemical, Sanyou, Aoyang, Grace, Yamel, Nanjing Chemical Fiber and Jilin.

Infinited

During 2022, Infinited Fiber Company announced plans to build a commercial-scale factory to produce Infinna, its regenerated textile fibre, at Stora Enso’s previously mothballed Veitsiluoto paper mill in Kemi, a Finnish city on the northern shore of the Baltic Sea.

The cost of the investment is estimated at €400 million and is expected to create around 270 jobs in the area. The annual fibre production capacity of the planned factory will be 30,000 metric tons – equivalent to the fibre needed for about 100 million T-shirts – with first commercial product scheduled for January 2026.

Infinited’s technology enables cotton-rich textile waste to be transformed into Infinna – a versatile, high-quality regenerated textile fibre which looks and feels like cotton.

The magic in the company’s process happens when urea reacts with cellulose, creating a carbamate functionality that gives the new fibre unique qualities like its soft and natural look and feel, superior dye uptake, and naturally occurring antimicrobial properties. As a more sustainable option to cotton, polyester and viscose, it is extremely versatile and has been demonstrated to work in the existing manufacturing supply chain.

Purchase Commitments

In a radically new approach that departs from the way the textile industry business has traditionally been conducted, major international fashion and apparel companies including Bestseller, H&M Group, Zara’s parent company Inditex, Pangaia, Patagonia, and PVH Europe (known for the Tommy Hilfiger brand) have already committed to Infinna purchases through multi-year agreements with Infinited.

As a consequence, Infinited will start business in 2026 from the enviable position of being almost completely sold out for several years.

In addition, the company has been building a supplier network for its textile waste feedstock by partnering with forerunning textile sorters across Europe, including a three-year agreement with Soex, the leading German textile sorting and recycling group, which will supply the Veitsiluoto plant in Finland with up to 5,000 tons of post-consumer textile waste annually.

“We are not only building a factory, but an ecosystem, and this contract with Soex is another great advancement in building the partner infrastructure for our flagship factory,” said Jari Ekblad, Infinited’s chief supply chain officer. “The collaboration will also bring our brand customers new opportunities to loop textile waste from their supply chains into our raw material.”

Demand

Based on extensive analysis, Infinited estimates that the annual demand for cotton-like recycled fibre will be over 4.5 million tons by 2030. The currently announced capacity commitments in the market indicate that demand significantly exceeds the supply.

As a result, Infinited intends to accelerate Infinna capacity build-up by shifting to establishing further plants, in close partnerships, targeting an annual production capacity of 500,000 tons by 2030.

The company has initiated a site search for the next two Infinna factories which need to fulfil a similar set of requirements to the plant in Finland, including access to renewable energy, a central location in terms of logistics and feedstock availability, and access to the textile manufacturing supply chain of customers. It is expected that one of the next two sites will be in Europe and the other in Asia.

Renewcell

A similar new business model has been established by Renewcell, which opened the first-ever industrial scale chemical textile-to-textile recycling facility in November 2022 in Sundsvall, Sweden, and dispatched the first shipment of Circulose dissolving pulp produced at the Renewcell 1 plant in December last year.

With an initial annual capacity of 60,000 metric tons, Renewcell 1 will be scaled up to produce 120,000 metric tons of pulp each year – the equivalent to 600 million T-shirts.

Circulose is derived from the recovery of cellulose from worn-out clothing and transformed into a dissolving pulp made from 100 per cent recycled textiles. The pulp serves as the foundation for various types of regenerated fibres, including viscose, lyocell, modal, acetate and other man-made cellulosic fibres. Currently, viscose made with Circulose is available from suppliers including Tangshan Sanyou and Yibin Grace, both based in China.

Renewcell also has a multi-year supply agreement in place with Austria’s Lenzing, under which it will supply the fibre manufacturer with between 80,000 to 100,000 tons of Circulose over a five-year period.

Suppliers

In June this year, Renewcell launched the Circulose Supplier Network (CSN) – a group of 47 yarn and textile producers helping to drive the circular economy forward by steadily supplying Circulose fibre to the market.

The CSN is comprised of early adopters becoming the first to access volumes of the product. By joining the network, members are committing to the continuous development of circular solutions and will play a vital role in moving sustainable textiles and end-products under the Circulose brand name to the mass market.

“The implementation of the Circulose Supplier Network is integral to the continued scaling of the product,” said Renewcell CEO Patrik Lundstrom. “With availability across the textile supply chain, fashion brands now have numerous circular options to design and create clothing with Circulose.”

Renewcell also continues to develop co-branding partnerships with some of the world’s most influential and recognisable brands, including Arket, Ganni, H&M, Levi’s, Pangaia, PVH and Zara.

At ITMA 2023, Switzerland’s Saurer also announced a partnership with Renewcell, and demonstrated Circulose being spun on all three of its industry-leading spinning systems – rotor, ring and air.

Spinnova

Spinnova has developed a unique method for mechanically refining pulp raw materials and transforming them into fibre suspensions ready for spinning without any harmful chemistry and involving no dissolving or regeneration processes.

On spinning into filament, the suspension flows through a unique nozzle at a high pressure which causes the fibrils to rotate and align with the flow to create a natural textile fibre. The fibre is then simply dried and collected, ready for spinning into yarn.

This fibre can be upcycled in the process again, without dissolving or harmful chemicals, making it possible for a product to be taken back from the consumer by brands, delivered to the process and ground back into micro fibrils without even dismantling the product.

The upcycled fibre is said to be just as good, if not better quality than the original fibre and can be turned into new products without having to add any fresh fibres at all.

This is such a recent finding that the company is still in the process of making further trials with brand partners to validate how many times the process can be repeated.

Because of the way the pulp is processed, almost any cellulosic biomass can be used and although wood is currently the selected raw material, Spinnova has also explored leather waste, agricultural waste such as wheat straw, as well as cotton waste. Its leather waste-based development with Ecco is already a joint venture that is building a pilot production line in Finland.

One Million Tons

In June this year, Spinnova and Suzano – the world’s largest pulp producer – officially opened the first commercial-scale facility producing wood-based Spinnova fibre in Jyvaskyla, Finland. Operated by Woodspin, a joint venture between the two companies, the plant will produce 1,000 tons of sustainable, recyclable and fully biodegradable textile fibres from responsibly grown wood each year.

This facility is the first industrial operation for Suzano outside Brazil and Woodspin has also announced plans to open a second site to further scale production. The aim is to build annual production capacity to one million tons of Spinnova fibre by 2033.

“At Woodspin we are bringing Spinnova’s biodegradable textile fibre to the market, made using Suzano’s abundant supply of responsibly sourced eucalyptus pulp,” said Christian Orglmeister, executive director of new business at Suzano. “This has a radically lower environmental impact than alternative fibres such as cotton, offering one of the few genuinely scalable solutions to support sustainable production. We are excited to ramp up production and create positive change.”

Footprint

Capable of producing textile fibres with zero emissions, the modern facility also has a comprehensive approach to circularity and sustainability. The only by-product of Spinnova production is heat, so the facility does not require an environmental permit to operate. Using an advanced energy recovery system, excess heat is recycled into the local district heating system and estimated to save 2.4 kg CO2e per kg of fibre produced that would otherwise be required to generate district heat.

Coupled with an environmentally friendly production process, Woodspin’s large-scale facility saves more emissions than it creates.

“Spinnova’s patented fibre production process does not require any harmful chemicals or dissolving, nor does it generate waste or microplastics,” explained the company’s CTO Juha Salmela. “It has a 74 per cent smaller life cycle carbon footprint and uses 99.5 per cent less water compared to conventional cotton production. The result is a natural, cotton-like textile fibre that meets the rigorous environmental and performance demands of brands and consumers alike – and, through facilities such as this one, can now be produced at scale.”

In the most recent development, a Rieter yarn spinning line originally planned for Spinnova’s plant in Finland, will now be installed at the facility of Tearfil in Guimaraes, Portugal, following a product development agreement between the two companies.

Spinnova brand partners include Adidas, Bergans, Bestseller, Halti, H&M, Marimekko and The North Face.

Treetotextile

Meanwhile, in March this year, the €35 million regenerated cellulose fibre demonstration plant of TreeToTextile started up at Stora Enso’s Nymolla mill in southern Sweden.

The venture is owned by H&M Group, Inter IKEA Group, Stora Enso and LSCS Invest, and construction of it commenced in Spring 2021. Its initial production capacity will be 1,500 tons of fibre per year prior to scale-up and commercialisation of the technology.

The new regenerated cellulosic fibre is produced from renewable and sustainably sourced raw materials from forests using less chemicals and water than the conventional industry.

Norratex

And in further fibre innovation from Finland, Nordic Bioproducts, a spin-off from Aalto University, is the owner of patented AaltoCell technology which has been explored for textile fibre production for several years.

Using the patented method, cellulose is first processed into small-particle cellulose, after which it is further processed into a viscose-like textile fibre.

Nordic Bioproducts has now succeeded in developing a new plant-based textile fibre called Norratex which is manufactured without any toxic chemicals or expensive solvents.

Norratex fibre can be made from forest industry by-products, textile waste and ordinary paper pulp and its properties are described as “close to viscose, with cotton-like properties”, but with the longer-term potential to also become a replacement for polyester.

Drop-In Solution

The new fibre making process is being viewed as a drop-in solution for existing viscose fibre plants, to eliminate the use of toxic carbon disulphide, and could also offer a route to the recycling of mixed material textiles because on a laboratory scale, natural fibres have already been neatly separated from plastics into clean fractions.

A €30 million pilot production plant is now being built in Lappeenranta in south-east Finland close to six existing pulp manufacturing plants, with an annual capacity of approximately 10,000 tons of Norratex and backing from CMPC Ventures.

“We are very excited about this new collaboration,” said Bernardita Araya, manager of CMPC Ventures. “For CMPC, it represents a significant step towards establishing a leading role in the development of the future of biobased industries with global impact. This technology is easy to scale for producing fibres in a suitable price range and there has been a lot of interest from the market. We are in a good position to take this product quickly to commercialisation. Competition in the field of new textile fibres is accelerating and the first players in the industry are already commercialising their products and approaching industrial-scale production.”

Conclusion

All of these inspiring developments in Scandinavia point to a more sustainable future for the textile industry, but they are certainly not being developed in isolation. Closer cooperation across the supply chain – from raw materials suppliers to the apparel brands and across every continent – is now very evident. Legislation – such as the European Union’s new Strategy for Textiles, which will be introduced in 2025 –is also playing a part in uniting many of the players in a highly complex and fragmented industry in need of a streamlined and more sustainable new global structure.