Technical lignins, which are the byproducts of the pulping industry, have a high potential to be used as value added products. In principle, the complex structure of lignin is a good prerequisite for using it as an additive for different applications. In our work, we investigated the use of two types of technical lignins in surface sizing formulations for packaging papers with the target to better understand the influence of the physico-chemical properties of laccase polymerized and raw technical lignins on the development of paper strength and hydrophobicity. Prior to surface sizing the lignins are purified by ultrafiltration and precipitation respectively. The solubility of the lignosulfonate at neutral pH was achieved straight after the ultrafiltration process. The solubility of the precipitated kraft lignin at neutral pH was not ensured after the purification process and therefore an additional solubilization process was performed. Water solubilized precipitated kraft lignin and ultrafiltrated lignosulfonates were polymerized using laccase at neutral or slightly alkaline conditions. An increase in strength properties of lignin sized samples was observed which was in the same range or slightly better compared to starch sized samples. The substrates sized with the enzymatically modified technical lignins showed a significantly higher hydrophobicity compared to the raw lignin sized samples while the strength properties remained on the same good level. Ongoing work is focusing on a further improvement of the performance of technical lignins in surface sizing of packaging grades by optimization of the enzymatic polymerization process.<br/>

Utilization of polymerized technical lignins in the development of surface sizing formulations for packaging papers

253rd National Meeting (2017)

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