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Dutt, D., Jain, R. K., Maheshwari, A., and Kaur, H. (2011). "Cost reduction studies of decorative laminates," BioRes. 6(2), 1495-1504.

Abstract

Barrier paper, which is made of bleached absorbent kraft pulp, is a significant layer of decorative laminates, since it controls the see-through of brown color of saturating kraft paper and its opacifying effect usually is achieved by a heavy loading of TiO2. The TiO2, due to its very small particle size, passes between the cellulosic fibers and drains into the white water. To overcome this problem, papermakers try to use various retention aids for improving overall retention of TiO2, but agglomeration of TiO2 causes a decrease in light scattering efficiency of TiO2. During the subsequent saturation operation, the air in the voids is replaced by melamine formaldehyde, which has a refractive index close to that of cellulose. As a result, the sheet becomes translucent and poses 'see through' problem. Keeping this in view, anhydrous magnesium silicate is used as an extender with TiO2 because it effectively increases the overall filler retention, sheet brightness, opacity. The dispersed aqueous slurry of anhydrous magnesium silicate forms fine gel that entraps TiO2 in the wet web and prevents removal of fines and fillers. The addition of 25% TiO2, 7% micronized soapstone powder, 8% anhydrous magnesium silicate, 1% melamine formaldehyde, and 0.1% sodium hexameta-phosphate was found to improve the overall retention by 65.25% and to cut the manufacturing cost by US$ 546.00 per tonne of pulp without affecting the product quality.
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