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Biogranules for industrial foils and a new class of products

Biogranules are a starting point for the production of a wide range of novel biobased materials: in a BMBF-funded project called ”EnzymaCell”, a company called TECNARO and its cooperation partners have developed thermoplastic biofoils. The innovative combination of cellulose and natural additives has led to a material with many application possibilities.

Extrusion of the granules results in a biofoil, which can, for example, be used as a decorative element in the interior of vehicles. © TECNARO GmbH

TECNARO GmbH, based in the Baden-Württemberg city of Ilsfeld, specialises in the development and production of innovative biomaterials. It has developed a biopolymer known as “liquid wood”, composed of lignin and natural fibres such as hemp or flax. The company also focuses on another wood component, i.e. cellulose, which is also present in large quantities in plants like cotton. As part of EnzymaCell, a project funded by the German Ministry of Education and Research (BMBF), TECNARO and its cooperation partners from academia and industry have developed thermoplastic, flexible biofoils based on cellulose. Dr. Dirk Schawaller is coordinating the project at TECNARO and explains what makes these biofoils so special: “We use novel cellulose-based materials with very specific characteristics, which ensure that the final products have excellent elasticity and transparency.” The goal of the project was to produce foils with functionalities that made them suitable for use as decorative element in car interiors and as protection and wrapping foils. As the project progressed, the researchers found that the granules developed by TECNARO could also be used for other products and applications.

EnzymaCell was established in early 2013, bringing together a team of project partners that was specifically selected for the development of thermoplastic biofoils. A company called Zeisberger Süd-Folie GmbH based in the city of Asperg specialises in the processing of foils. Its task is to examine the new material for its suitability for perforating, welding and printability. Benecke-Kaliko AG from Hannover is a supplier to the automotive sector and has developed a foil extrusion method that enables the granules to be turned into flat foils. “We have provided Zeisberger Süd-Folie GmbH and Benecke-Kaliko KG with tonnes of granules so that they can optimise the process technology to make it possible to produce foils with the desired properties,” says Schawaller going on to add, “DST Dräxlmaier Systemtechnik GmbH from the city of Vilsbiburg has developed the application profiles of the foils and defined the market requirements.”

Modified cellulose is key to new biomaterials

Dr. Dirk Schawaller is head of the BMBF-funded project “EnzymaCell” at TECNARO GmbH. © Dr. Dirk Schawaller

Schawaller and his team – involving on occasions over half of TECNARO's staff – that developed the granules were at the beginning of this pipeline. The Institute of Technical Biochemistry (ITB) at the University of Stuttgart was also involved in the starting phase of the project. “The plan was to modify cellulose using enzymes to make it thermoplastic, i.e. mouldable at elevated temperatures. We wanted to make use of the moderate reaction conditions of biocatalyses instead of using chemical processes,” says Schawaller. The researchers wanted to find a way to control the material’s thermoplasticity by way of the enzymatic treatment of cellulose involving specific carboxylic acid derivates. The University of Stuttgart’s Institute of Polymer Technology (IKT) was able to turn the first samples into foils on a small scale.

However, as often happens in R&D, the new approach was unsuitable for industrial upscaling. The resourceful TECNARO team was able to overcome this obstacle by also using two commercially available cellulose derivatives alongside their own cellulose granules. “We have developed a solution concept and are now using thermoplastic biopolyesters as additional components, resulting in thermoplastically processable compounds with very interesting property profiles. As soon as the ITB in Stuttgart manages to industrially upscale the enzymatic treatment step, we will be able to integrate this concept into our processes,” says Schawaller.

An unexpected discovery increases the application possibilities

TECNARO’s biobased granules can be processed into different materials. © TECNARO GmbH

Meanwhile, the new material has opened up completely unexpected possibilities, as Schawaller explains. “The project has enabled us to generate new materials for which we already have pilot customers. As part of our own research, we have discovered that the combination of biopolymers and cellulose derivatives leads to a material with strong shrinkage effects. This material is very transparent.” The bottom line is that the project has led to promising developments. As part of TECNARO's product portfolio, the granules will be available for the production of foils. Moreover, the TECNARO team is already working on the further development of the granules for even more applications.

“The product class is also interesting for the production of injection-moulded parts and as a renewable resource for soft PVC, for example sealing rings or suction cups,” says Schawaller, emphasising that the team is specifically focused on biobased materials. He comments: “Our company aims to replace petroleum-based products with biobased products of the same or better quality. Customers are more interested in stability and durability than in degradability. However, should our customers become more interested in biodegradability, we will also be able to develop products that suit this purpose.” The new materials therefore fit perfectly into the company’s philosophy of bringing sustainable products made of renewable raw materials to market, and thus contribute to reducing the consumption of fossil resources such as petroleum.

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