Increased recyclability of wet strengthened liquid packaging board, through synergetic effects of combining CMC and PAE – a case study in full scale

Abstract There is an ever-increasing demand for renewable, recyclable and biodegradable packaging solutions, from consumers, producers of goods, and producers of packaging materials. Closing the material loop and increasing recyclability of fiber-based package materials is one of the keys to move forward towards a more sustainable future. While the recyclability rates of fiber-based packaging are high, packaging boards with high wet-strength can pose problems due to problems with repulping. This manuscript investigated the possibilities to reduce the use of polyamide-epichlorohydrin resins (PAE) by supporting the process system with carboxy-methylated cellulose (CMC) through machine trials in mill scale production. The focus of the investigation was on the wet-strength of the board product and the repulpability value. The results given from the full-scale trial were positive, indicating a potential in using CMC while reducing the PAE addition. The results showed that wet tear strength and wet tensile strength of the board were maintained, while higher repulpability rates were given, encouraging better recyclability of the board material. This will be beneficial to the environment both with lower use of non-renewable chemicals and possibilities for higher degrees of recycling of the board products.