Spring 2009 Newsletter    Nanometric Evolution of Papermaking	John Penniman
In the late 1970s Allied Colloids started commercializing the use of bentonite and a cationic chemical.  There were reports of trials on a Swedish newsprint machine; it was clear they were trying to feel their way forward. About the same time, Eka Chemical introduced colloidal silica and cationic starch, based significantly on research conducted at Centre Technique in Grenoble, but never widely publicized. Over the years, the Allied Chemicals cationic chemical evolved into a POLYDADMAC, poly-di-allyl-di-methyl-ammonium-chloride, which had the merit of being variable in molecular weight and also, through the di-allyl component, attractive to anionic trash. Acceptance increased for both systems, and many variants came to market.  The common theme remained:  anionic nanoparticle and cationic, charge-neutralizing, counter-particle.  Our new nanometric papermaking starts with these two building blocks, and goes beyond them, in four significant ways. First, we reduce the interfacial tension by about two-thirds, thereby extending nanoparticle scaling down to molecular dimensions.  Instead of relying on bundles of cationic chemical to neutralize the nanoparticle, we utilize molecules, reducing chemical usage by more than 90%. Second, we carefully balance the electrostatic charge of the system at zero zeta potential.  This ensures the best possible balance between formation and retention at minimum chemical usage. Third, we operate under closed loop computer control at the lowest available specific filtration resistance (SFR), thereby maximizing productivity. Fourth, we now have the option on a high speed, modern machine of extending the reduced interfacial tension into the press and dryer sections, thereby reducing dryer energy usage by 40-60%. Respond to:  john-penniman@papermaking-chemistry.com Return to Home Page