Skip to main content

Innovative structured polysaccharides-based materials for recyclable and biodegradable flexible packaging

Periodic Reporting for period 2 - SHERPACK (Innovative structured polysaccharides-based materials for recyclable and biodegradable flexible packaging)

Reporting period: 2018-12-01 to 2019-11-30

The flexible packaging materials’ market is forecast to grow at a three percent rate to 2020 – the main drivers including cost and sustainability – while being dominated mainly by PE and PP. The main drawbacks are that PE and PP are not biodegradable and films are difficult to recycle, not to mention multilayer materials.
As an alternative, SHERPACK aims at developing an innovative high barrier, renewable, biodegradable and recyclable flexible paper‐based packaging material, that can be easily converted by heat‐sealing and folding, with improved stiffness and grip, in order to replace materials such as plastics or aluminium foil currently used on the market by an advanced biomaterial. The first market targeted is flexible packaging materials for dry food, evaluated at 1.6 million tons per year and 3.7 billion euros (Europe, 2020).
A multidisciplinary and complementary consortium of six partners has been set-up for achieving the objectives, including three RTOs and three industrial groups from five European countries. An advisory group consisting of a major end-user, a retailer and a packaging machine manufacturer is also involved to help define requirements and ensure the relevance of the new material with the value chain.
The new material relies on three major innovations that will be developed from TRL 3 up to TRL 5: (i) a wet-lamination process used to add a thin layer of fibre specialty on the cellulosic substrate to provide a superb barrier to contaminants and oxygen; (ii) the formulation of a biodegradable polymer waterborne emulsion and its subsequent coating on the substrate to provide excellent heat sealability and barrier to water vapour; (iii) the specific design and application of a grid to improve the specific stiffness and the grip. The three innovations will then be assembled to deliver two proofs-of-concept. Last but not least, all the developments will be assisted by a Life Cycle Assessment to prove their environmental benefit.
Since the beginning of the project, a wet-lamination process was used to add a thin layer of cellulose fibrils on the cellulosic substrate to provide a superb barrier to contaminants and oxygen. The process parameters have been optimised to reach the target of oxygen barrier and the outstanding results on the barrier to contaminants have been confirmed in various conditions (time, temperature, relative humidity). Concerning the formulation of a biodegradable polymer waterborne emulsion, the selection of the polymer and the optimisation of the emulsion process parameters allowed producing stable emulsions that exhibit sufficient concentration. Its subsequent coating on the cellulosic substrate required further formulation to reach satisfactory rheological properties and the targeted coat weight. Further work on the polymer confirms that this layer should be easily heat sealable, however the results obtained on the coated paper have not reached the properties targeted in the project, yet. Some alternatives from the market have been tested but are not quite satisfactory, and others are still being investigated. Polysaccharides have been formulated and coated on the substrate, first by rod coating and then using a screen-printing process for printing of a grid on the material. Both processes confirmed a great improvement of the specific stiffness when the right conditions are met. The three technologies have been assembled to produce the first and second proofs-of-concept, successfully. The final properties reach the target for grammage, thickness, oxygen barrier, barrier to contaminants, and stiffness. However, improvements are still needed for water vapor barrier and heat sealability. Finally, the first biodegradability and recyclability tests are also very positive, and the compliance of the material with food contact regulations and recommendations is still under study, but with good preliminary results in terms of composition criteria.
- The oxygen barrier obtained using the thin layer of cellulose fibrils is better than most polymers used today, and with a grammage close to or lower than that of aluminium for similar uses. It is expected that this process will have been developed at pilot scale at the end of the project: the machine has been installed at the end of 2019 and trials might be organized in the frame of the project by end November 2020.

- It is also believed that before the end of the project, a biodegradable polymer waterborne emulsion will be formulated and represent an alternative to the use of PE for heat-seability and water vapour barrier.

- The deposition of a polysaccharide grid through screen-printing has been achieved at lab scale, allowing for a significant reduction of grammage of packaging materials while maintaining the necessary mechanical properties.

- The yield of recycling was close to 100% for the first materials developed in the project, instead of 50-70% for the reference materials from the market. At industrial scale, this would have a huge impact on both the economy of recycling and the environmental impact of flexible packaging.
Synthesis of Sherpack