| 摘要 |
<p>The invention provides a method of recovering and recycling waste coating color from papermaking coating process for use as wet end filler. The inventive method overcomes many technical challenges inherent in using waste coating colors as wet end filler such as the coatings having fine pigments that hurts sheet strength more than regular filler, having strong anionic charge and tendency to disturb wet end chemistry, causing excessive foaming, and containing a large amount of hydrophobic binder particles that tend to agglomerate in the white water and deposit on papermaking equipment. The method involves mixing the coatings with fresh filler particles, adding de-foaming agent, adding cationic coagulant, then preflocculating the mixture. This process causes fresh filler particles, pigments and binders in waste coating color to agglomerate together and form stable flocs with defined particle size distribution. Moreover, using such agglomerate as wet end filler was found to improve sheet strength properties by taking advantage of the binding ability of the latex or binders contained in the waste coating color.</p> |
