Influence of fines on sheet delamination in Condebelt drying and recyclability of...

Application: This study may allow papermakers to produce better linerboard from recycled furnishes containing significant amounts of fines without sheet delamination problems in Condebelt drying.

Fines that impede drainage and vapor permeation were thought to be the prime cause of a

As fines content increased, sheet delamination became more severe. Fibril-like secondary fines caused more delamination than did primary fines. Since Condebelt drying proceeds unidirectionally, variation in z-directional vapor permeability of the web plays a critical role in sheet delamination. Results showed that as fines content in the bottom layer decreased, so did the level of delamination.

Dong-Il Paper installed flotation units to separate fines from the bottom layer stock and added the separated fines to the middle ply stock. This kept the bottom side of the sheet more permeable to water vapor, while keeping the top side free from contaminants. The combination of technologies of fines fractionation by floatation, three-ply forming, and Condebelt drying successfully produced quality linerboard from recycled furnish.

We also investigated the disintegration and recycling characteristics of Condebelt- and cylinder-dried papers. Strong inter-fiber bonds formed in Condebelt drying delayed disintegration of fibers in the early stage of disintegration, but there was no problem in disintegrating the Condebelt dried linerboards. Recycled paper properties depended upon the final drying process employed, irrespective of the drying process used in previous recycling stages. S!

Lee, Youn, and Ham are with the Department of Forest Products, College of Agriculture and Life Sciences, Seoul National University, Suwon, 441-744, Republic of Korea; Kim is with Dong-Il Paper Mfg. Co., Ltd., Moknae-Dong 492-1, Ansan, Kyungki-Do, 425-100, Republic of Korea; Jung is now with Hansol Paper Mfg. Co. Ltd., Whachon-Ri 481-8, Changhang Up, 325-908, Republic of Korea. Email Lee at lhakl@plaza.snu.ac.kr.