- Can you provide insights into TAU’s role as the leader in pilot-scale extrusion coating trials? How do these trials contribute to the production of coated paperboard using polyester blends, and what are the main criteria TAU evaluates during these trials?
TAU has developed the pilot-scale extrusion coating line that is used in the project and has been involved in number of university and industry driven projects where the coating polymers as well as the paperboard substrates have been developed. This has enabled us to develop an insight and routines on how to evaluate materials performance in an industrial scale extrusion coating process, what properties need to be concerned for the further processing steps and for the function ability of the end product. The trial runs enable us to evaluate how the polyester blends perform under the challenging conditions of the extrusion coating process, where the material is subjected to relatively high temperatures and combinations of high shear and extension rates. From rheological point of view this means that the melt must have appropriate drawdown ability and elasticity. One main criterion TAU uses to evaluate the materials performance is how low coating weights (coating thicknesses) can be reached while still maintaining uniform coating layer without pin holes or other imperfections and without experiencing instabilities in the process like draw resonance. Another important evaluation criterion is the adhesion of the coating material on the substrate that must be at sufficient level. The performance of the polyester blends is benchmarked against marked-established polymers for paper coating.
- In the testing of plastic-coated paperboard for food packaging items, TAU collaborates with SE and CTP. Could you elaborate on the specific role TAU plays in assessing barrier properties and heat sealability of the coated paperboard? How do these results inform the optimization of polyester blends in the project?
Heat sealabilty and barrier properties of the coated paperboard are important features considering its further conversion to a food package item and its function ability as a food package material. The heat sealing may happen with different methods like hot bar, hot air and ultrasonic. TAU will evaluate the heat sealability by performing the heat sealing with selected method(s) and further testing the attained seal strengths to make sure that the seal has adequate properties.
The barrier properties have direct impact for example on self-life of a food product and are therefore one of the key properties for a food package material. TAU will perform water vapor, oxygen and grease permeability tests on the coated carboards to evaluate if the barrier properties are at sufficient level. The results from the tests enable us to evaluate if the polyester blends fulfill the requirements or if the blend recipe should be modified. The results can also be used to study how thin coating layers can be used while still maintaining required functional properties.
- TAU is involved in testing material performance for mulch film application in collaboration with BASF. Can you discuss the testing process for paper-based mulch films and the key parameters TAU evaluates? How does feedback from farmers influence the optimization of mulch film compositions?
The performance of the polyester coated paperboards in mulch film application is evaluated by comparing them to an existing product in field tests. The coated paperboard can have improved biodegradation rate and mechanical properties compared to currently existing products while minimizing the amount of plastic that is needed in the structure. TAU is not involved in the actual field testing but will prepare the polyester coated paperboard samples for the tests. The assessed characteristics for the mulch films are for example mechanical properties and time of stability in and on the soil. High enough mechanical properties are important to ensure that the film does not break during placement. The properties should also maintain long enough in the soil and under different environmental conditions (moisture, UV-radiation, microbes) so that the crop is protected, but the film should still biodegrade in reasonable time after the service. The mulch film composition could be optimized based on the feedback from the farmers by changing the paperboard thickness or type, by changing the coating layer thickness or by changing the recipe for the polyester blend.
- As part of the evaluation of converting and pilot-scale repulping trials, TAU collaborates with CTP, BASF, and SE. What challenges does TAU anticipate in scaling up the repulping process, and how does the company plan to address them? Additionally, could you explain TAU’s role in assessing the quality of fibre pulp generated from the repulping process and its implications for polymer fraction recycling?
TAU’s role in the repulping trials is to supply the coated paperboard for the repulping trials. A possible risk with the polyester blends is that they would influence the repulping process in such way that the quality or quantity of the fibre pulp generated by the repulping process would be reduced. Addressing of the issue might require optimization of the polyester recipe or adjusting of the coated paperboard structure. TAU is not directly involved in the quality assessment of the fibre pulp or end of life treatment of the polymer fraction.