Effect of Refining on Softwood Pulp with Addition of Eucalyptus for Greaseproof Paper Production : Vacuum Dewatering in Laboratory Scale

Abstract: We are provided countless products from the forest industry and has been through many years. Paper, paper board, packaging materials and furniture to mention a few. A special type of paper used in food packaging for example, is greaseproof paper. Many producers of greaseproof papers use the toxic and harmful group of chemicals called per- and polyfluorinated alkyl substances (PFAS) in coating since they possess grease resistance. Nordic Paper is a manufacturer of iamKraft® kraft paper and greaseproof paper with over a hundred years of experience without the use of PFAS. Without PFAS, they instead rely on excess refining to form a very dense paper. Nordic Paper has decided to introduce the addition of eucalyptus fibers to the softwood sulfate pulp to enhance the formation of the paper. This study aims to investigate the effects of ~20% addition of eucalyptus fibers to softwood sulfate pulp in regard to refiner energy expended, air permeance (as a measure of grease resistance) and formation. Laboratory work has been done on hand made sheets with a vacuum suction box in laboratory scale. Eight different pulps (four with addition of eucalyptus), provided from Nordic Paper Seffle AB, Säffle, with different refining degree was used in this study. The vacuum pressure used was 20 kPa through all tests, with dwell times 0, 1, 2.5, 5, 10, and 20 ms on sheets with a grammage of 50 g/m2. The study has shown that the pulp with ~20% addition of eucalyptus achieved 86°SR with only 82% expended energy relative to the softwood pulp, which had a refining degree of 87°SR. This small difference in refining degree led to a similar development in dewatering after 20 ms dwell time and 20 kPa, where the softwood pulp achieved a dryness of 9.2% and the pulp with addition of eucalyptus achieved 9.0% dryness. The formation of the softwood pulp was worse, which was the reason for the implementation of addition of eucalyptus. The air permeance on the other hand was not improved by the eucalyptus, but more data is needed to confirm since it is based on only one occasion. So, if the air permeance (grease resistance) allows, Nordic Paper Seffle AB may be able to save 20% in expended energy for refining of softwood sulfate pulp with addition of eucalyptus.