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Process developments for a recyclable and compostable all-cellulose multilayer material for packaging

Periodic Reporting for period 2 - CelluWiz (Process developments for a recyclable and compostable all-cellulose multilayer material for packaging)

Reporting period: 2020-12-01 to 2021-11-30

Packaging is necessary to transport and protect food and goods and communicate with the end-user. The food packaging industry has always been agile to follow consumer expectations and societal changes. This industry is nowadays under a great pressure from both authorities and consumers to improve its environmental and sustainability credentials in the coming years. So there is a need for the development of a new generation of packaging that has at least the same technical performances as today’s mono or multi-materials but with a demonstrated recyclability and biodegradability.
CelluWiz overall objective is to develop two processes able to produce an all-cellulose packaging material that can offer a competitive alternative to existing multi-layers plastic materials or multi-materials used in the packaging sector while being renewable recyclable/recycled in the paper waste value chain and biodegradable. These two innovative processes, the MFC wet lamination process and the chromatogeny coating and grafting process will be combined to produce three proofs of concept: clamshells, cups and trays. The environmental benefits of the innovative processes and materials and their easy integration into the value chain, will be assessed by performing Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) with accurate and relevant data.
The project started on June 1st, 2019. The first months were devoted to the supply of raw materials and to the production and the characterization of reference materials. These materials were produced combining a laboratory scale production of MFC wet laminated boards with a pilot chromatogeny grafting. The reference materials were dispatched to the partners for testing. It was shown that these materials were suitable for the clamshell market while being perfectly recyclable and biodegradable. Clamshells, cups and trays were designed taking into account the material properties and first proofs of concepts of clamshells and trays were made and proved the concept of the project.
Several devices and facilities were designed and commissioned during the first eighteen months of the project : a new device for hygromechanical testing of the materials, a small-scale MFC wet lamination pilot, a new laboratory fatty acid chloride gas grafting device, an improved chromatogeny grafting pilot, a platform for marine biodegradability. All these equipements will help understanding and developing further the MFC wet lamination and chromategny grafting processes to produce all-cellulosic packaging materials for the clamshells, cups and trays markets.
After 30 Months of work, the following major scientific and technological achievements can be pointed out:

From WP2
• MFC wet laminated board reels were produced with oil barrier values close to the target after improvements on the pilot machine (new replication system, IR dryer and work on filtration media).
• High adhesion of the MFC layer to the board is proved with plasma pretreatment regardless the board grade.
• A minimum MFC amount of 16 g/m² is required today to reach a good oil barrier of 2 g/m².
• The sorption model developed showed good prediction of the trends for both MFC films and board.
• Curl of the laminated board is induced by the MFC film behavior, while it presents no influence on non-linear hygro-expansion.

From WP3
• A methodology to investigate the grafting in the z-direction has been implemented
• Samples with ultra-high grafting densities has been obtained after having developed a new technology to open the MFC films
• The chromatogeny process has been up-graded by adding steam boxes after the grafting that has significantly increased the grafting efficiency and the converting ability of the MFC wet laminated board

From WP4
• Raw material including different board and MFC grades has been delivered to all WPs according to their wishes.
• Coarse elements removal in an MFC suspension by screening through fine wire opening has been proven in device developed at lab scale.
• Deflocculation in an MFC suspension by screening in a semi-industrial size pressure screening pilot plant at up to 2,7% concentration has been repeated and shown stable.

From WP5
• Plasma treatment improves MFC layer adhesion without negative effects on barrier properties
• Steam box after grafting improves convertability due to higher moisture content
• Heat sealing agent can be coated and the material can thereafter be heat sealed

From WP6
• A realistic & reliable scenario for the CelluWiz LCA has been defined to compare the environmental impact of the CelluWiz cup proofs of concept with the conventional fully plastic (PS) cups and board laminated with plastic layer cups
• Analytical tests for BfR XXXVI requirements compliance shows that the grafted CelluWiz materials accomplishes with the cadmium and lead content and aluminium migration
To reach Celluwiz overall objective, four specific objectives have been defined:
1-Develop the wet lamination process. This process assembles, without glue any papers and boards with a MicroFibrillated Cellulose (MFC) layer thus creating a stratified cellulosic material. This MFC layer will bring stiffness, lightweighting, barrier to air, grease and oxygen. At the end of the project, a small pilot machine will be able to produce small reels of MFC wet laminated board.
2-Develop the chromatogeny coating and grafting process for MFC layers. This process is an ultrafast and efficient solvent free chemical grafting able to turn hydrophilic cellulosic materials into hydrophobic materials. CelluWiz will make possible to re-think the chromatogeny coating and grafting process to reach ultrahigh grafting densities on MFC layers in order to create a micron size layer of cellulose ester which will bring water/liquid resistance and water vapour barrier without impairing the recyclability and/or biodegradability.
3-Produce 3 proofs of concept all-cellulose materials: Clamshells, Cups, and Trays. The proofs of concept performances will be at least equivalent to the market references and will also be biobased, recyclable in the paper value chain, biodegradable in compost and in marine environment.
4-Demonstrate the environmental benefits of the innovative processes and materials and their easy integration into the value chain, by performing Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) with accurate and relevant data.
The associated KPIs are 1-the reduction of the carbon footprint by at least 30% just by substituting the material in comparison with recyclable fossil-based materials and by up to 70% compared with non-recyclable product and 2- the reduction of the disposals costs by 100%, since the solution will be fully compostable and/or recyclable
CelluWiz targeted proofs of concept
CTP's chromatogeny pilot machine
CTP's MFC wet lamination laboratory equipment
CelluWiz sample