Effects of White Water Recirculation on the Performance of Optical Brightening Agents

本研究主要探討手抄紙迴流白水次數對於OBA影響紙張增白效果的影響，以作為OBA實廠應用時對於紙張白度變化的推估依據。實驗變數為OBA種類（2S-OBA及4S-OBA）、添加量(0、0.3、0.6、1.2、2.4%)及白水迴流次數（0~7次），白水檢測PCD電荷、酸鹼值、OBA保留率，手抄紙檢測白度及灰份。實驗結果顯示，在配料過程中，闊葉木漿及CaCO3不會明顯影響白水電荷，OBA及陽性澱粉為影響白水電荷的主因。4S-OBA會明顯影響PCD，但2S-OBA則影響不明顯。OBA種類或添加量對pH不會有明顯的影響。2S-OBA組中OBA添加量或迴流白水次數，對於白水中PCD及pH的影響不明顯。4S-OBA組中的PCD隨著OBA添加量及迴流白水次數而更趨負電性。迴流白水次數對於pH的影響則較不明顯。2S-OBA組的OBA迴流留存率及灰份隨著添加量增加而上升；而4S-OBA組則隨著添加量增加而下降。在相同添加量下，4S-OBA組的增白效果較2-OBA組為佳，同時4S-OBA組的色調穩定度較2S-OBA組為高。

關鍵字

螢光增白劑；白水迴流；造紙；濕端添加；紙張白度；增白效應

並列摘要

In this study, we investigated the effects of the number of white water recirculation rounds on the whitening performance of added optical brightening agents (OBAs). The results could be useful in practical mill application to determine the variability estimates when using OBAs in printing and writing paper production. The variables of this study included OBA types [disulfo-OBA (2S-OBA) and tetrasulfo-OBA (4S-OBA)], dosage (0, 0.3, 0.6, 1.2, and 2.4% of the dry pulp), and the number of white water recirculation (0~7) rounds. The particle charge (PCD), pH, OBA retention, etc. of the white water samples were tested. The brightness, apparent whiteness, and ash content of the handsheets prepared from each round were tested. Results of this study indicated that during the stock preparation process, the bleached hardwood kraft pulp (BHKP) and calcium carbonate filler did not notably affect the electrical charge of white water; while the addition of OBA and cationic starch modified the white water charge balance. The addition of 4S-OBA significantly influenced the PCD; while the effect of adding 2S-OBA was less significant. Adding either OBAs had no appreciable effect on the white water pH value. In the 2S-OBA group, the OBA dosage and number of white water recirculation rounds had little effect on the PCD of the white water; whereas in the 4S-OBA experimental group, with an increasing dosage and number of white water recirculation rounds, the PCD moved toward more-negative charges. The recirculation retention rates of the 2S-OBA and ash (filler) increased with its dosage and the number of white water recirculation rounds; those of the 4S-OBA, however, decreased with increasing dosage and number of white water recirculation rounds. Under the same dosage, the 4S-OBA tended to have a better whitening effect than the 2S-OBA. Also, the tonal stability of the 4S-OBA was superior to that of the 2S-OBA.

並列關鍵字

optical brightening agents ； white water recirculation ； whiteness ； brightness ； effect on whiteness

國際替代計量

Effects of White Water Recirculation on the Performance of Optical Brightening Agents

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