Changing Quality of Recycled Fiber Material. Part 1. Factors Affecting the Quality and an Approach for Characterisation of the Strength Potential

The paper recycling sector has undergone major changes in recent years, particularly regarding the quantity and quality of various materials processed. Material originating from board grades will increasingly dominate the recycling market as the use of printing papers decreases and the amount of non-fiber elements increases. Users of recycled fiber material have to overcome three main challenges: price, quality, and availability. This paper focuses on the quality dilemma in terms of measurement needs and possibilities from the user viewpoint. It includes a discussion of the factors causing deterioration in the quality of paper used for recycling. Today, the average fiber age is low compared to what the fibers can tolerate. Therefore, the characteristic phenomena in the paper recycling loop are not caused by the degradation of individual fibers, but by a blending process in which different fiber grades and non-fiber components are blended in a non-optimal way. A novel method is introduced in this article for evaluating the quality of recycled fiber material using a new parameter, the fiber integrity value. Part 2 of this paper will focus on the application of this new parameter and demonstrates its correlation with paper properties.