Papermaking Nanometrics: Maximize Cost Efficiency and Quality

PAPER CHEMISTRY LABORATORY, INC.
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Winter 2006 Newsletter

Papermaking Nanometrics:
Maximize Cost Efficiency and Quality
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John Penniman

Introduction
The central compelling concept in papermaking is perceived as nanoscience, where inter-molecular physical forces dominate. Cost-efficiency and quality result from carefully balancing the Nanometrics to maximize their effect.
Zeta Potential
The author’s laboratory did over 5000 controlled experiments, in which the electrostatic particulate charge, or zeta potential; and specific filtration resistance, or drainage; were measured as process parameters. A handsheet was made, and sheet ash, sizing and Scott Bond were measured from it.
Our first exciting conclusion was that maximizing the process parameters, retention and drainage, resulted in maximizing the physical property parameters, such as sizing and Scott Bond. We were tempted to think that perhaps it was a perfect world, with all in proper balance. In fact, it was our first major clue as to the importance of inter-molecular proximity.
Van der Waals Force Our second exciting conclusion occurred when we controlled one experiment close to zero zeta potential, with the second experiment uncontrolled and equilibrating at some negative value. The result in the controlled case was higher sheet ash, accompanied by higher Scott Bond.
We concluded that the counter-intuitive result was caused by van der Waals force, which increases exponentially to the 6^th power as inter-molecular distance decreases. This was our second nanoscience insight.
Thoroughness of Mixing
It would appear to be intuitively logical that the inter-molecular distance between chemical and stock would be beneficially decreased by increasing thoroughness of mixing. Chemists agree that wet end mixing has not been sufficient to the task on real world high speed machines. On-line instrumentation quantifies the insufficiency by taking a chapter from the six sigma doctrine. Zeta potential standard deviation is measured as a function of thoroughness of mixing, and should not exceed 0.65mV.
Modern, high speed machines with complex chemistry have a typical zeta potential standard deviation of 4-5mV accompanied by an unacceptable frequency of machine breaks and excessive chemical usage. A Principal Cause of Machine Breaks is Lack of Thorough Mixing.
It was left to a clever Finnish engineer, Jouni Matula, to develop the TrumpJettm, for which he was first importantly recognized in 2003. TrumpJettm technology has grown into a small family of what Jouni calls “booster pumps.” They are oriented vertically to pipe flow, and introduce a stream of additive at low concentration relative to the stock stream, under great pressure and high speed, facilitating mixing.
The TrumpJettm is now so widely used that it obviously performs a cost-effective service. In particular, Jouni claims that functional chemical additive usage can be reduced by about 10%.
Preferential Wetting
Carefully controlled laboratory experiments were executed, in which small amounts of a functional chemical additive were added to ca 20#/t (1%) of an innocuous hydrocarbon liquid, with the low surface tension of 24 dynes/cm². The quality of dispersion of the additive in the stock was so much improved that we were able to reduce its usage by one to two orders of magnitude.
Preferential wetting functions by diffusion. A similar hydrocarbon has long been used for introducing silicone defoamer to papermaking stock. Surface tension is measured by a sensor and controlled by the Zeta Data computer. ExxonMobil has signed off on environmental concerns; recycling is simple. The Albany International variable speed press section pilot plant, in Albany, NY, was used to conduct a preferential wetting efficiency study. Results showed that the low surface tension liquid could greatly reduce water re-wetting in the first press, as a function of machine speed, the faster the better. The amount was surprising: up to a 25% reduction in dryer section energy. Hydrodynamics is a key factor, as the phenomenon is not observed on old, slow recycle board machines.
In the dryer section, the low surface tension liquid preferentially wets the cellulose, eliminating the hydrogen bonding of water to cellulose, thereby greatly reducing the energy requirement for water removal.
Nanoparticulate Process
Nanoparticulate processes were introduced about 1980, based on nanoparticles such as colloidal silica, termed by Eka Nobel Compozil^tm; or bentonite, by Allied Colloids (now Ciba), and marketed as Hydrocol^tm.
In principle, the nanoparticulate process is of particular value in addressing difficult process tasks, including stock high in filler and/or fines. Properly executed, retention and water removal can be increased without adverse effect on formation or physical properties and with maximum productivity.
This takes place in two steps. An appropriate charge-neutralizing cationic chemical is added until the entire stock is at a target, positive zeta potential, in the range +5 to +10mV, or higher if more structure is desired. Next, sufficient (highly negative) nanoparticle is introduced to precisely reduce the positive charge to zero zeta potential.



The electrostatic balance thereby created provides an open structure of the filler + fines + fibers and nanoparticles, all bound together by electrostatic attraction, because of the precisely correct amount of cationic and anionic chemicals.



The key word is BALANCE. It is the mutual attraction of the positive and negative particles that creates the structure so conducive to water removal and retention. The charges must be precisely balanced, or negative effects occur. The imperfect structure impairs water removal and retention, and excess surface charge exerts a repulsive effect, further impairing retention and also degrading strength.



Prevailing papermaking technology, using cationic demand measurement for control, is counter-productive because it leaves a residual repulsive negative charge. Additionally, a conventional "retention aid" is added to achieve retention and drainage by macroflocculation. Process parameters and physical properties are degraded, with major negative influence on retention, drainage, formation and strength.

On the other hand, under closed loop control of chemical feed rates, the charge-balanced system is flexible. Flow rates of the cationic chemical and the nanoparticle can be increased or decreased in tandem, while maintaining a final balance of zero zeta potential, in order to maintain an optimum structure, and continuously maximize process parameters, physical properties, and productivity, despite variation in stock composition. Maximizing productivity has a major positive impact on cost effectiveness.
Summary and Conclusion
Inter-molecular phenomena exert key beneficial influence on both the papermaking process and physical property parameters.
The following listed improvements should result from strict adherence to the principles of nanotechnology, as a definitive central concept:

Productivity increase of 5-15% while maintaining maximum process and physical property parameters

More efficient use of chemicals, with cost reduction of 90% or more

Decrease in dryer energy usage up to 25% on a high speed machine

A significantly higher level of absolute quality and performance, accompanied by a high and impeccable level of quality uniformity

Conclusion: Papermaking can be accomplished at significantly lower cost and much higher quality by observing the principles of nanotechnology.

John G. Penniman

www.papermaking-chemistry.com



Winter 2006 Newsletter Papermaking Nanometrics: Maximize Cost Efficiency and Quality	John Penniman
Introduction The central compelling concept in papermaking is perceived as nanoscience, where inter-molecular physical forces dominate. Cost-efficiency and quality result from carefully balancing the Nanometrics to maximize their effect. Zeta Potential The author’s laboratory did over 5000 controlled experiments, in which the electrostatic particulate charge, or zeta potential; and specific filtration resistance, or drainage; were measured as process parameters. A handsheet was made, and sheet ash, sizing and Scott Bond were measured from it. Our first exciting conclusion was that maximizing the process parameters, retention and drainage, resulted in maximizing the physical property parameters, such as sizing and Scott Bond. We were tempted to think that perhaps it was a perfect world, with all in proper balance. In fact, it was our first major clue as to the importance of inter-molecular proximity. Van der Waals Force Our second exciting conclusion occurred when we controlled one experiment close to zero zeta potential, with the second experiment uncontrolled and equilibrating at some negative value. The result in the controlled case was higher sheet ash, accompanied by higher Scott Bond. We concluded that the counter-intuitive result was caused by van der Waals force, which increases exponentially to the 6^th power as inter-molecular distance decreases. This was our second nanoscience insight. Thoroughness of Mixing It would appear to be intuitively logical that the inter-molecular distance between chemical and stock would be beneficially decreased by increasing thoroughness of mixing. Chemists agree that wet end mixing has not been sufficient to the task on real world high speed machines. On-line instrumentation quantifies the insufficiency by taking a chapter from the six sigma doctrine. Zeta potential standard deviation is measured as a function of thoroughness of mixing, and should not exceed 0.65mV. Modern, high speed machines with complex chemistry have a typical zeta potential standard deviation of 4-5mV accompanied by an unacceptable frequency of machine breaks and excessive chemical usage. A Principal Cause of Machine Breaks is Lack of Thorough Mixing. It was left to a clever Finnish engineer, Jouni Matula, to develop the TrumpJettm, for which he was first importantly recognized in 2003. TrumpJettm technology has grown into a small family of what Jouni calls “booster pumps.” They are oriented vertically to pipe flow, and introduce a stream of additive at low concentration relative to the stock stream, under great pressure and high speed, facilitating mixing. The TrumpJettm is now so widely used that it obviously performs a cost-effective service. In particular, Jouni claims that functional chemical additive usage can be reduced by about 10%. Preferential Wetting Carefully controlled laboratory experiments were executed, in which small amounts of a functional chemical additive were added to ca 20#/t (1%) of an innocuous hydrocarbon liquid, with the low surface tension of 24 dynes/cm². The quality of dispersion of the additive in the stock was so much improved that we were able to reduce its usage by one to two orders of magnitude. Preferential wetting functions by diffusion. A similar hydrocarbon has long been used for introducing silicone defoamer to papermaking stock. Surface tension is measured by a sensor and controlled by the Zeta Data computer. ExxonMobil has signed off on environmental concerns; recycling is simple. The Albany International variable speed press section pilot plant, in Albany, NY, was used to conduct a preferential wetting efficiency study. Results showed that the low surface tension liquid could greatly reduce water re-wetting in the first press, as a function of machine speed, the faster the better. The amount was surprising: up to a 25% reduction in dryer section energy. Hydrodynamics is a key factor, as the phenomenon is not observed on old, slow recycle board machines. In the dryer section, the low surface tension liquid preferentially wets the cellulose, eliminating the hydrogen bonding of water to cellulose, thereby greatly reducing the energy requirement for water removal. Nanoparticulate Process Nanoparticulate processes were introduced about 1980, based on nanoparticles such as colloidal silica, termed by Eka Nobel Compozil^tm; or bentonite, by Allied Colloids (now Ciba), and marketed as Hydrocol^tm. In principle, the nanoparticulate process is of particular value in addressing difficult process tasks, including stock high in filler and/or fines. Properly executed, retention and water removal can be increased without adverse effect on formation or physical properties and with maximum productivity. This takes place in two steps. An appropriate charge-neutralizing cationic chemical is added until the entire stock is at a target, positive zeta potential, in the range +5 to +10mV, or higher if more structure is desired. Next, sufficient (highly negative) nanoparticle is introduced to precisely reduce the positive charge to zero zeta potential. The electrostatic balance thereby created provides an open structure of the filler + fines + fibers and nanoparticles, all bound together by electrostatic attraction, because of the precisely correct amount of cationic and anionic chemicals. The key word is BALANCE. It is the mutual attraction of the positive and negative particles that creates the structure so conducive to water removal and retention. The charges must be precisely balanced, or negative effects occur. The imperfect structure impairs water removal and retention, and excess surface charge exerts a repulsive effect, further impairing retention and also degrading strength. Prevailing papermaking technology, using cationic demand measurement for control, is counter-productive because it leaves a residual repulsive negative charge. Additionally, a conventional "retention aid" is added to achieve retention and drainage by macroflocculation. Process parameters and physical properties are degraded, with major negative influence on retention, drainage, formation and strength. On the other hand, under closed loop control of chemical feed rates, the charge-balanced system is flexible. Flow rates of the cationic chemical and the nanoparticle can be increased or decreased in tandem, while maintaining a final balance of zero zeta potential, in order to maintain an optimum structure, and continuously maximize process parameters, physical properties, and productivity, despite variation in stock composition. Maximizing productivity has a major positive impact on cost effectiveness. Summary and Conclusion Inter-molecular phenomena exert key beneficial influence on both the papermaking process and physical property parameters. The following listed improvements should result from strict adherence to the principles of nanotechnology, as a definitive central concept: Productivity increase of 5-15% while maintaining maximum process and physical property parameters More efficient use of chemicals, with cost reduction of 90% or more Decrease in dryer energy usage up to 25% on a high speed machine A significantly higher level of absolute quality and performance, accompanied by a high and impeccable level of quality uniformity Conclusion: Papermaking can be accomplished at significantly lower cost and much higher quality by observing the principles of nanotechnology.
John G. Penniman
www.papermaking-chemistry.com