Drainage Aid
Sub-microscopic particles of silicon dioxide suspended in liquid function as components of microparticle retention systems on high-speed paper machines. When used in combination with cationic polymers, colloidal silica produces extremely small, dense flocs that release water rapidly and improve paper formation. This inorganic additive carries a high surface area and a negative charge that attracts positive polymer sites on the fibers.
Sheet Formation
Papermakers apply this microparticle after the pulp has passed through the last high-shear zone of the stock prep system. This application timing allows the polymer to reform its bonds around the silica, creating a shear-resistant network. The resulting structure holds fine fibers and mineral fillers securely while permitting water to drain freely through the forming fabric.
Process Cleanliness
Reduced carryover of fine particles into the white water loop minimizes deposit formation on the press rolls and dryer fabrics. This cleanup prevents defects like pinholes and spots in the finished paper sheet, which are especially problematic for high grade printing applications. The additive also lowers the chemical oxygen demand of the mill effluent by retaining organic material in the sheet.
Operators measure the ash content of the paper to verify that the silica is successfully locking the mineral fillers into the fiber web. This routine test ensures that the mill optimizes chemical costs while maintaining the required paper opacity.
