Ji Young Lee·Chul Hwan Kim·Hae Min Jo·Kyung Min Kim·Su Ho Kim
diluted to a 0.5% consistency for handsheet prepa- ration. Handsheets with a grammage of 100±5 g/m 2 were produced according to TAPPI T205 sp-06 “Forming handsheets for physical tests of pulp” after D-FWA was added to the pulp slurry and mixed for 2 min at 600 rpm. The addition percent- ages of D-FWA were kept at 0.4%, 0.8%, and 1.2% of the oven-dried fibers. The handsheets were wet pressed at 345 kPa for 5 min and then dried at 120℃ using a laboratory wet press (model 326; Wintree Corporation, Japan) and a cylinder dryer (Daeil Machinery Co. Ltd., South Korea), respec- tively. The prepared handsheets were conditioned at 23℃ and 50% RH, and then analyzed. 4VSGBDFTJ[JOHPGQBQFSXJUIBTUBSDI TPMVUJPOUIBUJODMVEFE'8"T Preparation of the starch solution and surface sizing were conducted in the same manner as de- scribed in our previous studies. 8,9) The 10% starch solution was made by cooking oxidized starch at 90℃ to 95℃ for 30 min. After the temperature of the solution reached approximately 50℃, T-FWA or H-FWA was added, and the resulting solution was mixed for 30 min. The addition of the FWAs was kept at 10% and 20% based on the oven-dried starch. The surface-sizing process was conducted using a rod coater (HT-BC-ST, Hantech, Republic of
Korea). The topside of a never-sized sheet of paper was surface-sized, and the paper was then dried in an air dryer for 150 s. To prevent the surface-sized paper from curling, it was passed through a cylin- der dryer twice at 120℃. After the topside of the base paper was surface-sized, the bottom side of the paper underwent the same treatment. The final pickup weight was controlled at 2.0 to 2.5 g/m 2 for each side. The surface-sized paper was conditioned at 23℃ and 50% RH before analysis. Figure 1 shows a flow diagram of the preparation of model paper containing FWAs. 4JNVMBUJPOPGUIFSFDZDMJOHOVNCFSBOE NFBTVSFNFOUPGPQUJDBMQSPQFSUJFTPG UIFNPEFMQBQFSUSFBUFEXJUI'8"T The first round of recycling was performed by the disintegration of paper dyed with FWAs followed by subsequent handsheet preparation. 7) The disin- tegration of paper dyed with FWAs was carried out at a 2% level using a standard disintegrator; subsequently, handsheets with a grammage of 100±5 g/m 2 were made from the disintegrated pulp according to TAPPI T205 sp-06 “Forming hand- sheets for physical tests of pulp”. The handsheets were wet pressed at 345 kPa for 5 min and dried at 120℃ in a laboratory wet press and in a cylinder dryer, respectively. After each round of recycling, the handsheets were conditioned at 23℃ and
Fig. 1. Preparation of FWA-treated paper with (a) internal- and (b) surface-treating FWAs.
J. of Korea TAPPI Vol.51 No.2 Mar.-Apr. 2019 51
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