Summer 2008 Newsletter   FOUR FATAL FLAWS   of the   Papermaking Process	John Penniman
Introduction For a period of seven years in the 1990’s our laboratory employed a Russian professor of paper science as a bench chemist.  The mission was to employ modern instrumentation to explore and define the nature of papermaking chemistry.  More than 5000 experiments were conducted, mostly in the lab, and some on large machines.  We concluded that nanoscience must be invoked to explain the fundamental concepts of papermaking; and nanotechnology must be utilized for process development and control. Paramount among the so-called weak chemical bonds is one called van der Waals force.  It states that inter-molecular attraction increases inversely as the 6th power of the distance separating molecules.  The lab investigation showed that when we neutralized the repulsive electrostatic charge, we could use more filler and yet obtain a counter-intuitive stronger sheet:  a clear example of van der Waals force at work, as well as a demonstration of the significance of electrostatic charge. FATAL FLAW #1:  Failure to Mix Thoroughly By reducing the surface tension, from about 72 dynes/cm2  to about 24 dynes/cm2 , we were able to improve the mixing thoroughness of chemicals with stock by 1 or 2 orders of magnitude.  In other words, on a large machine, one could reduce the annual cost of sizing usage from $500K to the range of $5K to 50K. We conjecture that, in normal practice, the incompletely dispersed chemical remains in aggregated form, rather than dispersed down to molecular dimensions.  This hypothesis tends to be confirmed by the phenomenon of wet end “cationic decay”, long observed by many scientists. FATAL FLAW #2:  Failure to Neutralize the Repulsive Surface Charge Data taken from a coated free sheet (CFS) machine employing alkyd-ketene-dimer (AKD) sizing showed a high 0.71 correlation between zeta potential and sizing.  Clearly, zeta potential control is necessary to sizing efficiency. In the entire 160-year history of Fourdrinier papermaking, however, on-line control of electrostatic charge has never been reported, even with nanoparticle process chemistry.  Instead, macroflocculation is used to obtain an appropriate level of retention and drainage.  It causes poor formation and degradation of physical properties, including strength and printability.       FATAL FLAW #3:  Failure to Employ Wet End Computer Control Failure to employ computer control of chemical feed rates results in routine consumption of about 10X more internal size than necessary.  In the absence of effective control, it is considered necessary to use an excessive amount, in order to ensure maintenance of an adequate sizing level. FATAL FLAW #4:  Failure of Intellectual Integrity By way of introduction, the off-line cationic demand measurement is universally used to control the wet end of the papermaking process. On-line zeta potential measurement can be accomplished with a standard deviation of 0.5 to 1mV.  An on-line zeta potential system was installed on a specialty groundwood machine for a year, and a daily measurement of cationic demand was made by an expert representing the chemical supplier. The correlation coefficient of the zeta potential measurement with cationic demand was a low 0.17.  This experiment, with many others, provides compelling evidence that cationic demand measurement is not reproducible. In attending a papermaking conference in Helsinki, the author witnessed a paper on cationic demand as a means of process chemistry control.  When I went to one of the conference organizers to protest, arguably the leading chemistry professor in Europe, he put his hand on my shoulder, looked up and with great sincerity said, “John, everybody is partly right.” On a consulting assignment in Canada, at the invitation of a paper scientist who is arguably the leading professor in North America, I asked how reproducible is the cationic demand measurement?  He said, “John, that is a good question,” and the discussion was terminated.  The failure of leading professors to exhibit rigorous intellectual integrity and provide meaningful scientific leadership is, unfortunately, an endemic symptom of the cultural, structural and ethical deficiencies widespread in the paper industry, that are rarely acknowledged or discussed. John Penniman www.papermaking-chemistry.com