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Brown can be the new Green! Unbleached fibers for more sustainable tissue products
- Cláudia Vicente Esteves
- Fully bleached fibers are usually preferred in hygiene and tissue products due to their high brightness, water absorption capacity, and softness. However, environmental challenges require sustainable alternatives and unbleached fibers are becoming more frequent. The unbleached tissue products seen in the market are usually made from recycled fibers, which are not always the best and most sustainable alternative. Unbleached virgin fibers subjected to extensive oxygen delignification can instead be more sustainable and a better alternative - since fewer processes and chemicals are needed when compared to recycled or fully bleached fibers. Oxygen delignification has shown interesting potential by increasing the fibers' carboxylic acid content, leading to significantly higher fiber swelling and wet strength. The increase in fiber charges is even maximized when pulp presents high lignin content, leading to lower delignification and process energy requirements. Replacing fully bleached fibers with delignified fibers can reduce the environmental impact by lowering the carbon footprint from the bleaching process. The possibility of replacing fully bleached fibers with oxygen delignified fibers in tissue products was evaluated. High kappa number softwood pulps were subjected to kraft cooking and extended oxygen delignification and one fully bleached pulp was used for comparison. The study revealed the potential replacement of fully bleached pulps in tissue applications by unbleached pulps with a high fiber charge content – achieving higher wet strength and maintaining the absorption properties. Keywords: absorption properties, fiber charges, oxygen delignification, tissue, sustainability
