Still Marginal

Biobased textile fibres are not new. Nearly 130 years ago, in 1891, British chemists discovered how to make viscose from cellulose (from wood or cotton). The company Courtaulds bought the patents on the production processes. Industry historians remark that the era in which textile production and consumption has been dominated by synthetic fibres will constitute only a short intermezzo in the long history of textiles. The first totally synthetic fibre (nylon, a polyamide fibre) was detected in 1938. Then, a lot of other synthetic fibres emerged, like the highly successful polyester fibre, and fibres like polyacryl, polyethylene, popypropylene, aramide.

But it appears that after less than a century of market dominance by oil-based synthetic fibres, the textiles industry is returning to fibres made of biomass. Belgian research institute Centexbel, which organised the 3rd International Conference on Biobased Textiles on October 16, invited some twenty researchers from several Euopean countries to present the problems and results of their work.

A revolutionary raw material: CO2 

Researchers from ITA, the Institute for Textile Technology of Aachen University (Germany), promote the idea that the worldwide textiles industry should make the transition to what they call 'biopolymers of the third generation'. They argue that the textiles and fashion sector should abstain itself from competing for biomass with the food and feed sector. First generation natural polymers, like starch, and second generation synthesised polymers like PLA, may indeed be sustainable resources. And yet, it's preferable to use third generation polymers, this means polymers made from waste, like polyhydroxbuturate (PHB). Why? Because in a circular economy waste reduction is an important aim, and because food and feed-not textiles-should get priority to use biomass.

The German project CroCO2PETs (Cross-linkable CO2-polyether polyols) has the ambition to use carbon dioxide (CO2), an abundantly available gaseous waste product from industrial and houselhold processes, as a raw material in polymer production. At the same time, the project intends to contribute to climate protection by means of carbon capture and utilisation. The project aims at a reduction of up to 3 kg CO2-equivalent greenhouse gas emissions by the incorporation of only one kg CO2 into CO2-PET. Taking into account the global polyol production, these new polymers have the potential to reduce greenhouse gas emissions by an order of magnitude of 1 million tonnes per year. Moreover, the utilisation of CO2 as raw material vitalises an alternative carbon source, which can significantly reduce fossil depletion by chemical production.

The project is coordinated by Covestro AG, Leverkusen, Germany, a manufacturer of polymers and high-performance plastics. Covestro AG has successfully developed technology to develop carbondioxide based thermoplastic polyurethane. Now, in cooperation with researchers and manufacturers, the intention is to develop a textile process chain to establish carbondioxide-based thermoplastic polyurethane (CO2-TPUs) into the textiles industry. ITA has developed a spinning process at technical scale for CO2-based TPU. Among the first products from melt-spun CO2-based TPU filaments that are on show are: covered yarn, elastic tape, socks and stockings.

Competition with Asian polyester-based fabrics

One of the textile research projects that have received funding from the European Union's Horizon 2020 programme is the FIBFAB project. Researchers from four countries are working on this project: Spain (Aimplas), Turkey (Yunsa), Czech Republic (Sintex) and Belgium (Centexbel and DS Fibres).

The European Commission agreed to subsidise the efforts of FIBFAB because the aim of the project-the industrialisation of biobased textile fabrics for clothing applications-falls in line with two important goals of the European Union. One goal is ecological, the other one is economic.

There are good ecological reasons to replace the current European production of clothing fabrics (mainly made of cotton and wool fibres combined with polyester fibres) by fabrics made of biodegradable and sustainable polyactic acid (PLA) based fabrics, thus cotton/PLA and wool/PLA. Every year around one million tonnes of fabrics used for clothing applications, like casusal wear and work wear, are produced in Europe by yarn spinning combining natural fibres, especially cotton, and synthetic fibres, mostly polyester. However, these standard fabrics are complex to recycle after their use. They do not fit well in the circular economy for textiles that the EU wants to establish. So, the European Commission hopes that the research programme FIBFAB will successfully contribute to introduce in the textile market yarns and fabrics produced from PLA fibres and cotton or wool. It has been proved that PLA has better breathability, hydrophylic properties, UV resistance, low smoke production and flammability and lower density than polyester.

Furthermore, it is estimated that 10 million tonnes of textiles are discarded in Europe and America every year. Biodegradable textiles will provide an opportunity to avoid landfill and to increase recycling, since the separation and recycling of textiles containing entangled fibres of different nature is very complex and expensive.

The strategic economic reason to sponsor the FIBFAB programme is the current high dependence of Europe on Asian polyester fibres. The European Commission hopes that a newly developed textile supply chain based on 100 per cent biobased and biodegradable materials will make Europe less dependent on imports of synthetic fibres from Asia.

Progress with ups and downs

Just like the the transition from oil and gas to sustainable energy sources, also the transition from oil-based resources to sustainable resources will require a long and hard effort. In spite of the many alarming reports about greenhouse gas emissions and climate change, in 2018 oil demand continued rising by 1.5 per cent towards 97 million barrels a day. A June 2018 report on the global polyester staple fibre market, written by the research and consulting company Technavio, forecast that this market will grow at a CAGR (compound annual growth rate) of over 5 per cent in 2018-22.

It appears that emerging players who try developing sustainable processes and materials are usually no match for the established unsustainable fibre industry. Not only are their prices higher than current market prices for synthetic fibres, they also have a hard time to convince their potential customers that the new materials have the required functional proprieties.

At the Ghent conference, several companies described the long and costly struggle, often with ups and downs, to develop a biobased product and to find then a profitable market niche. Two examples.

A few years ago, Belgian SME Orineo created a material branded as Touch of Nature. Originally composed of a partially bio-based 2-component thermosetting binder and fillers derived from agro- and food-industry side-streams, this material had all the promises of a market hit. It stumbled, however, over REACH issues related to the fossil-based hardener. REACH is the European Union regulation concerning the Registration, Evaluation, Authorisation and restriction of Chemicals.

Instead of relying on external suppliers and technology, Orineo decided to develop internally a fully biobased hardener for its resin system. A successful breakthrough occurred on March 21, the first day of the 2018 spring, Orineo is now proud to announce the first fully bio-based thermosetting resin, commercially available and matching the technico-economical requirements of the targeted markets.

Researchers of high-ranking Dutch Avans University of Applied Sciences bought samples of all commercially available synthetic dyes to compare them with the biobased dyes they have developed. They tested the dyes on textiles and paper. They concluded that the natural dyes have the same functional properties as the synthetic dyes, except that they lack the required light authenticity.

However, synthetic dyes and excipients can be toxic and because of the highly developed stability are not degradable in the environment. The Avans researchers therefore continue developing more biobased colours from terrestrial and marine plants. They try to modify natural dyes by adding stabilisers such as anti-oxidants and UV-blockers or accomplish modification by encapsulation of the colour molecule or by using a carrier material.

But some researchers suggest that consumers should be educated to change their attitude towards colours. Most humans appreciate the continuous changing of colours they watch in nature. Why would they not accept changing colours in ageing textiles that are coloured with natural dyes?

Blow for Pef production

Just on the day of the conference-on October 18-the media reported about the intention of German chemistry group BASF to step out of a joint project with the Dutch renewable chemistry company Avantium to produce furandicarboxylic acid, the building block for Pef (polyethylenefuranoate), suited for many applications like carpet and textile fibres. Both companies had the intention to invest together €300 million to build a reference plant with an annual capacity of up to 50,000 metric tonnes per year at BASF's site in Antwerp, Belgium. The companies seem now to disagree on the timing. Anyway, Avantium remains determined to pursue the commercialisation of furandicarboxylic acid and Pef-with or without BASF.

Pef is said to be much more environmentally friendly than Pet (polyethylene terephthalate), the most common thermoplastic polymer resin of the polyester family which is used in fibres for clothing and many other products. Pef is made from fructose of cane sugar, corn and wheat.