| Summary: | 碩士 === 國立屏東科技大學 === 木材工業系 === 92 === Comparing to other fine grades paper , light weight coated（LWC）paper has shown significant growth lately both in production and consumption. Restricted by low coating amount, LWC’s properties consequently are affected by the characteristics and properties of the binder used. Acrylate latexes have found broader and broader market in an European and American paper industry due to many appraisable properties；SB latex, however, has almost occupied the whole market of coating binders in Taiwan and Japan. It is therefore time to explore the feasibility and potentiality of combining SA and SB latexes in acquiring better properties of LWC paper.
The results showed that the color’s water retention increased with decreasing particle size and glass transition temperature of SA latex. The higher viscosity thus induced created difficulties in the coating process. The effect of SB latex’s particle size on the coating color’s viscosity differed from that of SA, while the water retention of the colors increased with decreasing particle size, similar to that of SA latex. SA latex of smaller particle size observed the best smoothness, gloss, printed gloss and dry pick of LWC, except its opacity. The higher the glass transition temperature of the latex, the bulkier the coating layer. Paper smoothness and gloss were therefore much more improved after calendaring at 80℃ and above, while dry pick was not. Higher brightness, smoothness and gloss were obtained with the application of SA latex, while better dry pick was provided by the use of SB latex.
When SB latex was partially replaced by SA latex, colors perform a better water retention and viscosity. The smoothness, gloss and printed gloss of the LWC paper thus made were significantly upgraded. Paper brightness decreased with increasing SB latex mixing ratio in the binder prepared in our Lab. Smoother and less porous surface can be shown when SA250-SB100（the number shown in the lower letter are the particle size in nm）was the binder used in the colors, thus resulted into better smoothness, gloss and printed gloss of the LWC products. At a mixing ratio of 80/20, the combination of SA and SB latexes led to the best brightness and gloss, while the best pick was found as the ratio change to 20/80. The best dry pick derived from mixing SA latex of －9℃ Tg with SB latexes. Brightness, gloss and printed glass of the said product were inferior to the other combinations. The best printed gloss was found in combination of SA with 0℃ Tg and SB latexes. From our experience, SA latex of 250nm in size was found very easy to prepare. The best printability of LWCs could be expected when their kind of SA latex with 0℃ Tg was applied along with SB latex. Different combinations of SA/SB ratios, particle size and glass transition temperature of SA latex could produce LWC papers with market oriented properties.
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