From the Sector

The EU directive on the further development of sustainability reporting (CSRD) poses major challenges for companies and the public sector. Until now, the regulations have only applied to large capital market-oriented companies. However, far-reaching changes to sustainability reporting are expected when the CSRD is transposed into national law in 2024. The German Institutes of Textile and Fiber Research (DITF) are facing up to this challenge of external reporting and at the same time the responsibility for sustainable and resource-conserving science. The Textile Research Center has therefore set up a specialist department reporting to the Executive Board.

The DITF are reaffirming their commitment to sustainability with the appointment of the previous Head of the Competence Center Textile Chemistry, Environment & Energy, Dr.-Ing. habil. Thomas Stegmaier, as Chief Sustainability Officer (CSO). In addition to this new role, Stegmaier will continue to provide his expertise to the Competence Center Textile Chemistry, Environment & Energy as Deputy Head.

The task of the Chief Sustainability Officer is to develop solutions to reduce the DITF's energy and resource consumption, promote renewable energies and implement efficient energy use. The management team, the operational organizational units and all employees are involved in the process.

The CSO also acts as a driving force for both the Executive Board and the research departments to promote sustainability issues.

Textiles for technical applications often derive their special function via the application of coatings. This way, textiles become, for example wind and water proof or more resistant to abrasion. Usually, petroleum-based substances such as polyacrylates or polyurethanes are used. However, these consume exhaustible resources and the materials can end up in the environment if handled improperly. Therefore, the German Institutes of Textile and Fiber Research Denkendorf (DITF) are researching materials from renewable sources that are recyclable and do not pollute the environment after use. Polymers that can be produced from bacteria are here of particular interest.

These biopolymers have the advantage that they can be produced in anything from small laboratory reactors to large production plants. The most promising biopolymers include polysaccharides, polyamides from amino acids and polyesters such as polylactic acid or polyhydroxyalkanoates (PHAs), all of which are derived from renewable raw materials. PHAs is an umbrella term for a group of biotechnologically produced polyesters. The main difference between these polyesters is the number of carbon atoms in the repeat unit. To date, they have mainly been investigated for medical applications. As PHAs products are increasingly available on the market, coatings made from PHAs may also be increasingly used in technical applications in the future.

The bacteria from which the PHAs are obtained grow with the help of carbohydrates, fats and an increased CO₂ concentration and light with suitable wavelength.

The properties of PHA can be adapted by varying the structure of the repeat unit. This makes polyhydroxyalkanoates a particularly interesting class of compounds for technical textile coatings, which has hardly been investigated to date. Due to their water-repellent properties, which stem from their molecular structure, and their stable structure, polyhydroxyalkanoates have great potential for the production of water-repellent, mechanically resilient textiles, such as those in demand in the automotive sector and for outdoor clothing.

The DITF have already carried out successful research work in this area. Coatings on cotton yarns and fabrics made of cotton, polyamide and polyester showed smooth and quite good adhesion. The PHA types for the coating were both procured on the open market and produced by the research partner Fraunhofer IGB. It was shown that the molten polymer can be applied to cotton yarns by extrusion through a coating nozzle. The molten polymer was successfully coated onto fabric using a doctor blade. The length of the molecular side chain of the PHA plays an important role in the properties of the coated textile. Although PHAs with medium-length side chains are better suited to achieving low stiffness and a good textile handle, their wash resistance is low. PHAs with short side chains are suitable for achieving high wash and abrasion resistance, but the textile handle is somewhat stiffer.

The team is currently investigating how the properties of PHAs can be changed in order to achieve the desired resistance and textile properties in equal measure. There are also plans to formulate aqueous formulations for yarn and textile finishing. This will allow much thinner coatings to be applied to textiles than is possible with molten PHAs.

Other DITF research teams are investigating whether PHAs are also suitable for the production of fibers and nonwovens.

A lot of waste is generated in the trade fair and event industry. It makes sense to have furniture that can quickly be dismantled and stored to save space - or simply disposed of and recycled. Paper is the ideal raw material here: locally available and renewable. It also has an established recycling process. The German Institutes of Textile and Fiber Research (DITF) and their project partners have jointly developed a recycling-friendly modular system for trade fair furniture. The "PapierEvents" project was funded by the German Federal Environmental Foundation (DBU).

Once the paper has been brought into yarn form, it can be processed into a wide variety of basic elements using the structure winding process, creating a completely new design language.

The unusual look is created in the structure winding process. In this technology developed at the DITF, the yarn is deposited precisely on a rotating mandrel. This enables high process speeds and a high degree of automation. After the winding process, the individual yarns are fixed, creating a self-supporting component. A starch-based adhesive, which is also made from renewable and degradable raw materials, was used in the project for the fixation.

The recyclability of all the basic elements developed in the project was investigated and confirmed. For this purpose the research colleagues at the project partner from the Department of Paper Production and Mechanical Process Engineering at TU Darmstadt (PMV) used the CEPI method, a new standard test procedure from the Confederation of European Paper Industries.

Sensor and lighting functions were also implemented in a recycling-friendly manner. The paper sensor yarns are integrated into the components and detect contact.

Also, a modular system for trade fair and event furniture was developed. The furniture is lightweight and modular. For example, the total weight of the counter shown is well under ten kilograms and individual parts can easily be shipped in standard packages. All parts can be used several times, making them suitable for campaigns lasting several weeks.

A counter, a customer stopper in DIN A1 format and a pyramid-shaped stand were used as demonstrators. The research work of the DITF (textile technology) and PMV (paper processing) was supplemented by other partners: GarnTec GmbH developed the paper yarns used, the industrial designers from quintessence design provided important suggestions for the visual and functional design of the elements and connectors and the event agency Rödig GmbH evaluated the ideas and concepts in terms of usability in practical use.

Textiles are a given in civil engineering: they stabilize water protection dams, prevent runoff containing pollutants from landfills, facilitate the revegetation of slopes at risk of erosion, and even make asphalt layers of roads thinner. Until now, textiles made of highly resistant synthetic fibers have been used for this purpose, which have a very long lifetime. For some applications, however, it would not only be sufficient but even desirable for the auxiliary textile to degrade in the soil when it has done its job. Environmentally friendly natural fibers, on the other hand, often decompose too quickly. The German Institutes of Textile and Fiber Research Denkendorf (DITF) are developing a bio-based protective coating that extends their service life.

Depending on humidity and temperature, natural fiber materials can degrade in the soil in a matter of months or even a few days. In order to significantly extend the degradation time and make them suitable for geotextiles, the Denkendorf team researches a protective coating. This coating, based on lignin, is itself biodegradable and does not generate microplastics in the soil. Lignin is indeed biodegradable, but this degradation takes a very long time in nature.

Together with cellulose, Lignin forms the building materials for wood and is the "glue" in wood that holds this composite material together. In paper production, usually only the cellulose is used, so lignin is produced in large quantities as a waste material. So-called kraft lignin remains as a fusible material. Textile production can deal well with thermoplastic materials. All in all, this is a good prerequisite for taking a closer look at lignin as a protective coating for geotextiles.

Lignin is brittle by nature. Therefore, it is necessary to blend the kraft lignin with softer biomaterials. These new biopolymer compounds of brittle kraft lignin and softer biopolymers were applied to yarns and textile surfaces in the research project via adapted coating systems. For this purpose, for example, cotton yarns were coated with lignin at different application rates and evaluated. Biodegradation testing was carried out using soil burial tests both in a climatic chamber with temperature and humidity defined precisely according to the standard and outdoors under real environmental conditions. With positive results: the service life of textiles made of natural fibers can be extended by many factors with a lignin coating: The thicker the protective coating, the longer the protection lasts. In the outdoor tests, the lignin coating was still completely intact even after about 160 days of burial.

Textile materials coated with lignin enable sustainable applications. For example, they have an adjustable and sufficiently long service life for certain geotextile applications. In addition, they are still biodegradable and can replace previously used synthetic materials in some applications, such as revegetation of trench and stream banks.

Thus, lignin-coated textiles have the potential to significantly reduce the carbon footprint: They reduce dependence on petroleum-based products and avoid the formation of microplastics in the soil.

Further research is needed to establish lignin, which was previously a waste material, as a new valuable material in industrial manufacturing processes in the textile industry.

The research work was supported by the Baden-Württemberg Ministry of Food, Rural Areas and Consumer Protection as part of the Baden-Württemberg State Strategy for a Sustainable Bioeconomy.

The annual highlight of the industry is the International Conference on Cellulose Fibres in Cologne, where the latest innovations were showcased: new cellulose fibre technologies for various feedstocks and a wide range of hygiene and textile products as well as alternatives to plastics and carbon fibre for lightweight constructions.

This year, for the first time, there were 230 participants from 27 countries. About 60 were able to attend on site – with strict Corona safety measures – while the others were able to attend online and participate in questions and discussions.

The conference gave deep insights into the promising future of cellulose fibres, which fit perfectly into the current trends of circular economy, recycling and sustainable carbon cycles.

An important focus at the conference was alternative sources of cellulose. The increasing demand for cellulose fibres cannot be met in the long run with wood and used textiles alone. At the conference, a variety of agricultural by-products and biogenic waste were presented in presentations and panel discussions, such as orange and banana peels, grain and hemp straw. Much of this is high-volume and has not been put to high-value use so far. Exciting opportunities for the future cellulose fibre industry.

Innovation Award
Live at the conference, host nova-Institute and award sponsor GIG Karasek GmbH granted the “Cellulose Fibre Innovation of the Year” award to one of six highly interesting products.

• First Winner: Carbon Fibres from Wood – German Institutes of Textile and Fiber Research Denkendorf (Germany)
• Second Winner: Fibers365, Truly Carbon-Negative Virgin Fibres from Straw - Fibers365 (Germany)
• Third Winner: Sustainable Menstruation Panties: Application-driven Fibre Functionalisation – Kelheim Fibres (Germany)