Sustainable Binderless Product Technology

Currently lignocellulosic alternatives

Currently lignocellulosic alternatives for plastic packaging (e.g. paper) have poor water resistance, and poor water and vapour barrier properties. Therefore 100% lignocellulosic alternatives are only an option in very limited applications (e.g. egg boxes and paper trays). In the early 2000’s Wageningen Food & Biobased Research (WFBR) has developed and demonstrated a technology that is able to produce a high performance board from coconut husk.

Main achievements

Coconut husk was our starting point for further developing and getting more insight into the reaction mechanisms behind the success of the binderless board technology. Clear and detailed insights have been gained on the role and reactions of the coconut constituents in this process. These results have provided mechanistic understanding of reactions of the different biopolymers and their constituents and derivatives during binderless board production. We found out that the lignin content is an important parameter, but also the presence of other biopolymers seems to be important in the reaction mechanisms.

The optimal process conditions for coconut husk (particle size, moisture content, pressure and time) were used as benchmark and starting process parameters to use for different lignocellulosic feedstocks such as wood prunings, bamboo, hay, reed, flax, palm, leaf, miscanthus, sisal, abaca, jute, hemp, cocoa shell and cocoa husk. The (locally sourced) feedstocks were supplied by the different partners.

For most of these feedstocks it was possible to produce a good panel/board, but in some cases more optimization is needed to produce a higher quality board.

One of the findings in the mechanistic study was further evaluated by addition of a specific component (ultimately still derived from side-streams) in the pressing process. However these results were not satisfactory to optimize the process to industrial standards for example to decrease investment and processing costs. More research is needed to bring this closer to commercial application.

Overall, the binderless product technology can be used to produce good quality panels out of the different feedstocks, but the results in terms of mechanical strength, moisture resistance and look were found to depend on the composition and fibre/particle morphology of the lignocellulosic feedstocks. These results thus show that final board properties can be modulated by varying the input lignocellulosic feedstock, or using mixtures thereof – an important finding for further broadening the scope of the binderless board technology. Application oriented properties were tested and the screw resistance were good for all tested binderless boards. The coconut husk board showed good fire retardance properties, which is less pronounced for the softwood and hardwood prunings based board.