The problems you face as a papermaker will always be unique to your markets, and confined to some degree by your paper machine — even a new one….
The problems you face as a papermaker will always be unique to your markets, and confined to some degree by your paper machine — even a new one.
However, teaching your old machine new tricks or achieving greater flexibility at high speed with new machines is largely the result of interactive understanding of the wet end, and increased synergy across papermaking and coating. This is not to say that papermaking has nothing in common with techniques from the 1970s.
A snapshot of papermaking from three decades ago, compared to today, would reveal quite similar raw materials — fibre, water, chemicals, minerals, additives, sizing, latex and, of course, energy to drive the process. The primary difference is gains from synergistic relationships between the raw materials, differences in ratios, and the increasing use of a few important high performance ingredients. Silica nanoparticle systems, synthetic sizing, engineered pigments, and crosslinkers all play a critical role in optimizing properties in the sheet, and the ultimate satisfaction of end customers.
High tech papermaking
According to a German linerboard producer, commenting on the making of white top recycled grades on their new machine, “High tech papermaking requires high tech synergistic systems, especially concerning chemistry. We employ the most advanced nanoparticle technology at the wet end and expect our supplier to play a true partner’s role in helping us maximize its performance. We could use something less, but we wouldn’t deliver a superior surface for printers, or maximize productivity without it.”
According to Dr. Alvin Kirbawy, R&D manager at Simpson Tacoma, nanotechnology offers the bridging mechanism to better retention and formation. As Kirbawy puts it, “Losing control of retention translates to a serious water absorption problem on printing presses, and therefore printability.”
Kirbawy believes that achieving retention quickly on new machines is critical, because the turbulences are so high. “Without outstanding retention, we would overuse sizing, and we would have very dirty machines.”
At Simpson Tacoma they monitor their whitewater system continuously to maintain smooth operations. Kirbawy says, “We want the whitewater solids to be down pretty low, and know that solids are not building up, because that means we would be building up sizing.”
Kirbawy strongly emphasizes the move to higher end printing. He considers the ability to deliver crisp imagery to be closely tied to nanoparticle technology. In his words, “the nanoparticle system is critical to delivery top sizing performance, which means that we deliver a very smooth white top liner, not a mottled sheet.”
He notes that even agricultural markets are demanding high printing performance. Says Kirbawy, “Even an apple box is heavily printed. All black background with apples standing out is the norm. That demands high performance retention and sizing.”
New life for old machine
Europac’s mill in Alcolea de Cinca, northeast Spain, produces 70,000 tonnes/yr of semi-chemical fluting. They turned to high performance chemistry to increase output by more than 10%.
“We sought higher productivity and higher quality, and exceeded our expectations through the use of nanoparticle chemistry and a complementary wet strength agent,” said technical director of the paper division, Jos Castro.
Added Europac president, Jos Miguel Isidro, “When Europac is able to reduce costs of consumables, add value to the end products of customers, and improve the environment, why not continue to innovate?”
In addition to its pioneering work with silica nanoparticle systems at the wet end, Alcolea has also used chemistry to extend the life of machine clothing and run cleaner, employed scale solvents and high fusion level glues. They have also run trials for a new product to avoid fluffing in the driers, tested at only one other mill to date.
Eliminating interferences
Anyone familiar with complicated construction projects is aware of sophisticated modeling software, which enables architects, engineers and builders to eliminate interferences. Being reassured that piping is not on plan to go through steel and concrete is an obvious benefit. In a similar way, raw materials, which are not ‘modeled’ to work in concert will shut down effectiveness, and cause more serious problems, ranging from breaks, deposits and reduced quality.
Mark Zempel, market manager, retention with Eka put it this way, “Papermaking is a complex interaction of components and mechanisms, all at various strengths and stages and occurring at various rates. The history of paper chemistry is the history of harnessing these interactions to reduce negative side effects and variability, and to enhance the positive effects.”
Finding the right combination of components and mechanisms can result in true synergy, where more benefits are realized than with the individual components or with incorrect application. Synergy is a way to maximize the effectiveness of additives at the highest level of performance.
At Eurocan, Kitimat, British Columbia, producers of high-end liner and bag Kraft, continuous quality improvements remain the focus.
Said Brian Stevens, senior process engineer with Eurocan, “We are always looking at ways to improve paper properties, such as TEA, stretch, tensile, and porosity. We employ a nanoparticle silica and polymer system as the core vehicle, and we utilize a control system to help operators know exactly what’s going on at the wet end on a real-time basis.”
On the subject of synergy Stevens noted that, “We have matched retention system and dispersed rosin size system on our linerboard machine, which has increased stability, and lowered cost.”
Stevens values the potential of high performance chemistry to help them stay ahead of competition, and be leaders in the marketplace.
Burgo’s record speed LWC
The lightweight-coated paper line, PM9, installed at Burgo-Marchi’s Verzuolo paper mill in Italy, is an excellent example of the role of synergy from concept to the record speed they set for the production of web offset LWC.
Said Roberto Drago, who was corporate R&D chief from project conception in 2000 through 2002, “Once we chose the film coater for LWC, we selected strategic formulation suppliers, and then defined a precise development program. We encouraged Metso, Imerys and Dow to work together on every trial, and every part and process of operations.”
Alessandra Bogliano, R&D project manager, continued, “We made our first roll of paper only after the team considered hundreds of coating formulation options, and pilot tested for close to two years. It’s no wonder that we produced a quality sheet a few hours after start-up, and have run with the same recipes for close to four years.”
Noted Pekka Salminen, Dow’s global leader for latex, “The Verzuolo project required a fast pace to meet their objectives for starting up the machine. We worked closely with Imerys, Metso, and Verzuolo to overcome technical concerns. Five years of running smooth is the best proof possible for our mutual success.”
Salminen suggests that the close working relationship allowed the team to narrow in on key targets, and address issues effectively. As he put it, “We had one master pilot coater plan, allowing us to incorporate results from previous trials, and move forward in a progressive way.”
According to Bogliano, “The final result was the best result, because of the synergy achieved between the three companies, and ourselves. Excellent runnability and consistently high speed are not easy for anyone.”
Balance
Craig White, Eka’s market manager, coating additives & surface treatments, emphasized the importance of synergy throughout the process. He said, “A balance is needed in order to get the best quality finished sheet. There should be a balance with sizing and coating in order to he
lp control coat weight. Then of course to get a good sizing response you always need good retention of the sizing. So all aspects of papermaking affect each other.”
While some Canadian papermakers strongly support the employment of nanoparticles to enhance the base sheet to build quality from that point, others prefer crosslinker for many coating formulations. This method is considered preferable to some because of improved wet pick resistance, and due to the fact that traditional problems associated with moisture absorption on ten colour presses are no longer a concern.
In Brazil, another paper producer is improving its base sheet through application of zirconium at the off-line coater. Two Chinese mills have applied crosslinkers to produce better paper for book grades, also employing lower cost tapioca starch without any negative impact.
Properties booster
Tony Lyons, Imerys director of research, stressed the importance of synergy with pigments. He said, “In conventional printing grades the pigment provides gloss, smoothness, light scatter, shade and printability. Without a multi-pigment approach, sub-optimal compromises are often made. A good example is the trade-off between brightness/shade and opacity.”
Lyons believes that while brighter pigments give higher brightness paper, opacity will be sacrificed. He says that higher light scatter from engineered pigments, structured pigments and structured coatings through a multi-pigment approach allow, “both boats to float higher,” instead of having to choose one over the other. In SC grades carbonate pigments often provide a higher level of brightness, but printability will be sacrificed.
Added Lyons, ” Platy kaolin blended with the carbonate can bring balance back to the system by controlling the porosity of the sheet to provide the print performance desired while also achieving a higher level of brightness. Papermakers and paper coating operations are learning to take advantage of these synergies to give them new levels of performance while lowering their cost.”
Daniel Archambault, VP manufacturing, publications papers division for Kruger, Wayagamack (producers of LWC with a film coater), stands by the importance of carefully developed coating formulations and long-term partnerships with mineral and additive suppliers.
Archambault said they have continued to modify and improve their blend of GCC and Capim clay, working closely with suppliers to continue potential optimization.
Structure of synergy
Lyons sees the potential for synergy to be all about structure. In his words, “The creation of structure in the coating by using the right platy kaolin with PCC or GCC will allow a reduction in TiO2 usage in the coating. In the wet-end, platy fillers can control the coating holdout while allowing higher levels of carbonate to be used for brightness. Nano-engineering will be the next generation where controlled assembly of the coating structure may allow us to reduce binder demand in the coating and dial in the optimum structure for light scatter and print performance.” Lyons sees evidence of this with new fine platy pigments (nano-dimensional in their thickness) that actually increase the strength of the coating in certain situations and reduce binder demand. An open, well bound coating — with the right pigments on the top of the coating — could remove the gloss, optics and print triangulation frustration that dogs today’s coating chemist.
Where’s the money?
Dave Bakshi, marketing manager, Imerys commented, “Big gains have been made in the last decade using interactive/synergistic papermaking. Improved understanding and control of papermaking additives has led to a synergy of cost reductions and improved paper machine efficiencies. The next step is applying this knowledge to deliver breakthrough methods, unique paper properties, and strong financial results.”
Burgo-Marchi’s new R&D director Christian Naydowski offered a big picture view. “Long term success is not only about papermaking, coating, and better application of raw materials. True synergy is also about our own interactions with our customers, innovating with them in their businesses and the marketplace.”
Martin Koepenick of Innova International has been writing about paper industry innovation for over 20 years. Contact him at brandsmith@aol.
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