Ji Young Lee·Chul Hwan Kim·Hae Min Jo·Kyung Min Kim·Su Ho Kim
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T-FWA and recycled five times. H-FWA exhibited almost a 75% fluorescence reduction after five re- cycling processes. These results corresponded to the differences in the optical properties as a func- tion of the number of recycling rounds. The D-FWA reagent adsorbs on the cellulosic fi- bers via hydrogen bonding. 5) However, T-FWA and H-FWA are delivered to the surface of the paper by starch or other carrier chemicals, and there are no chemical bonds formed between T-FWA or H-FWA and the cellulosic fibers. 8) When white wastepaper containing FWAs was recycled, the starch or carrier chemicals can be extracted from the wastepaper with T-FWA or H-FWA. However, D-FWA was not intentionally extracted from the paper because it was attached to the cellulose fi- bers more strongly than T-FWA and H-FWA. Therefore, we concluded that D-FWA showed a much lower fluorescence reduction than T-FWA and H-FWA.
EJTUSJCVUJPOGSPNUIFDSPTTTFDUJPOPG UIFQBQFS The fluorescence emission images from the cross section of the paper were captured by CLSM to an- alyze the effect of recycling on the distributions of FWAs before and after recycling. Fig. 8 shows the D-FWA distribution before and after the recycling process. The D-FWA was distributed evenly in the cross sections of the paper before recycling, and the initial distribution of D-FWA was maintained until four rounds of recycling. Figs. 9 and 10 show T-FWA and H-FWA distributions before and after the recycling process. The T-FWA and H-FWA reagents were located on both surfaces of the pa- per, which means that T-FWA and H-FWA had a high level of surface holdout. 8) However, T-FWA and H-FWA were considerably desorbed from the paper, as the recycling process was preceeded, as shown in Figs. 6 and 7. Both T-FWA and H-FWA showed an especially similar distribution with that of D-FWA after three rounds of recycling.
Fig. 8. D-FWA distribution in the cross section of the paper containing 0.8% D-FWA before (left), and after (right) four rounds of recycling.
Fig. 9. T-FWA distribution in the cross section of the paper surface-sized with 10% T-FWA before (left), and after (right) three rounds of recycling.
J. of Korea TAPPI Vol.51 No.2 Mar.-Apr. 2019 55
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