Mid Sweden University

The fundamental approach of this research project is focused on how a typical Kraft pulping process can be modified to improve fiber properties to enhance important tissue product properties. The research work is to a large extent performed in laboratory scale at SCA R&D Centre. Process conditions tested in laboratory scale are largely based to the conditions prevalent at the present and in the near future possible new Kraft pulp fiber line at the SCA Östrand mill. Kraft pulp fibers have to be treated/ beaten in refiners to achieve appropriate bonding / adhesion properties when being used in tissue paper production. Refining is used to increased fiber surface area by means of fibrillation and to release fines (fine particles) from the fiber surfaces. In tissue production there is an aim to minimize the amount of free fines at the same time as increasing the fiber-fiber-bonding/adhesion.

Different approaches to increase the strength of the fiber-fiber joint will be tested in this work.

 - Firstly, can the refining energy necessary to reach certain tissue properties be reduced if the pulp fiber surfaces to a larger extent consist of very hydrophilic hemicelluloses, hemicelluloses? The aim here is to increase the strength of the fiber-fiber joints.

- Secondly, will it be possible to increase the proportion of hemicelluloses on the fiber surfaces by means of modifying a Kraft cooking process? Examples of methods used to modify the Kraft process are by changing the conditions in the digester (chemical profiling) and by adding new chemicals (different carbohydrate compound for example). 

- Thirdly, the strength properties can be increased in a cost effective way by post-treatment of the final bleached pulp.

The main goal with this project for SCA is to find cost-effective solutions for to achieve improvements of the following for tissue products important properties; softness, absorption and strength when the pulp production is based on softwood (spruce and pine).

The role as an industry PhD student is to work in the team of SCA´s development and a production personnel contributing to a better understanding of the softwood pulp fiber properties required for tissue paper production and contributes to the specifications of the quality of the product. Key features of the project are to produce tissue paper material with high absorption and softness and sufficient strength.