Key part of drainage-aid programs marketed by Eka Chemicals and Nalco; also capable of increasing the amount of cationic starch that can be retained as a dry-strength agent.
The conventional procedure is to add the colloidal silica very late in the approach flow to a paper machine, typically just after a set of pressure screens. A drainage rate increase is expected only if the furnish already has been treated with a suitable high-mass cationic polymer such as cationic starch or cationic poly-acrylamide. The effect is most pronounced when the net amount of cationic additives is enough to render the system at least slightly cationic before the addition of the micro-particle. For this reason it can be helpful to treat highly anionic furnish with a highly cationic material such as alum, poly-aluminum chloride (PAC), polyamine, or polyethyleneimine (PEI
Read more：http://www.chemical-chem.com/Papermaking-chemicals/Colloidal-Silica/
The conventional procedure is to add the colloidal silica very late in the approach flow to a paper machine, typically just after a set of pressure screens. A drainage rate increase is expected only if the furnish already has been treated with a suitable high-mass cationic polymer such as cationic starch or cationic poly-acrylamide. The effect is most pronounced when the net amount of cationic additives is enough to render the system at least slightly cationic before the addition of the micro-particle. For this reason it can be helpful to treat highly anionic furnish with a highly cationic material such as alum, poly-aluminum chloride (PAC), polyamine, or polyethyleneimine (
Read more：http://www.chemical-chem.com/Papermaking-chemicals/Colloidal-Silica/
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