Article Optimizing Fiber Quality in Recycled Old Corrugated Containers (OCC) Using Ultra-Fine Bar Plate Technology Min-Sik Park 1 , Chul-Hwan Kim 2, * , Hyeong-Hun Park 1 , Ju-Hyun Park 1 and Jae-Sang Lee 3
1 Department of Forest Products, Gyeongsang National University, Jinju 52828, Republic of Korea; tig05042@naver.com (M.-S.P.); bhh1217@naver.com (H.-H.P.); zdrxft1215@naver.com (J.-H.P.) 2 Department of Forest Products, Institute of Agriculture and Life Science (IALS), Gyeongsang National University, Jinju 52828, Republic of Korea 3 Department of Pulp & Paper Chemical Engineering, Gyeongsang National University, Jinju 52828, Republic of Korea; dmh6780@naver.com * Correspondence: jameskim@gnu.ac.kr; Tel.: +82-10943078896 Abstract This study evaluated the performance of ultra-fine bar refiner plates with a cutting edge length (CEL) of 97 km/s in enhancing the properties of Korean Old Corrugated Containers (KOCCs) compared to conventional plates with a CEL of 37 km/s. While unrefined KOCCs demonstrated compromised mechanical properties except for higher paper bulk, refining with the ultra-fine bar plate significantly improved tensile strength, tear strength, and water retention value (WRV). Although the conventional plate achieved higher stock throughput at lower specific energy, the ultra-fine bar plate proved more energy-efficient for achieving targeted fiber quality enhancements. The observed throughput plateau of the ultra-fine bar plate is attributed to its narrower groove design, which increases flow resistance. Overall, the ultra-fine bar plates offer a promising route for producing high-performance recycled paper by balancing refining energy inputs and fiber quality improvements.
Keywords: refining; ultra-fine bar plate; cutting edge length; fibrillation; KOCC
Academic Editor: Jordi Puiggali
1. Introduction The increasing global emphasis on sustainable practices has elevated the role of recycling within the paper industry, with Old Corrugated Containers (OCCs) serving as a primary source of recycled fiber. Recycling OCCs not only reduces environmental impact but also lessens reliance on virgin pulp resources, supporting both ecological and economic [1,2]. Within this context, refining is a critical step in the recycling process, as it enhances the mechanical properties and bonding potential of recycled fibers, thereby improving the quality of the final paper product [3]. Refining involves the mechanical treatment of pulp fibers to modify key characteristics such as flexibility, surface area, and fibrillation. These modifications are essential for strengthening fiber bonding and optimizing paper properties [4–6]. Among the various factors influencing refining efficiency, the cutting edge length (CEL) of the refining plates is particularly significant. CEL determines the nature and intensity of fiber treatment, directly impacting energy consumption, fiber modification, and the resulting paper quality [7–11]. Shorter CELs generally increase the intensity of fiber treatment, leading to greater fibrillation and improved bonding, albeit with higher energy consumption [7]. Conversely, longer CELs provide a gentler refining action, which can be advantageous for certain paper grades that prioritize fiber strength and integrity. This trade-off between fiber
Received: 23 July 2025 Revised: 7 August 2025 Accepted: 14 August 2025 Published: 15 August 2025
Citation: Park, M.-S.; Kim, C.-H.; Park, H.-H.; Park, J.-H.; Lee, J.-S. Optimizing Fiber Quality in Recycled Old Corrugated Containers (OCC) Using Ultra-Fine Bar Plate Technology.
Appl. Sci. 2025 , 15 , 9036. https://doi.org/10.3390/ app15169036
Copyright: © 2025 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/ licenses/by/4.0/).
Appl. Sci. 2025 , 15 , 9036
https://doi.org/10.3390/app15169036
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