By Steve Sena, S-Tec USA
In August of 2023, the American Forest & Paper Association (AF&PA) published research as to the extent of paper that gets recycled in the US. Nearly 68% of all fiber-based paper is recycled. A completely believable number if you are familiar with the industry. However, the same report claims that 93% of all old corrugated containers (OCC) are recycled in the US. That seems quite high. How are all the new recycle paper machines and container board mills that are being built finding capital investment if there is only 7% of recycled fiber available? There could be arguments made on how that data is being collected.
What is indisputable are the challenges working with a recycled fiber stream. Inconsistent fibers, fines, and contaminants being the top challenges. The challenges are unavoidable considering the source. However, there are several methods to control the most troublesome contaminant: adhesives that amalgamate and deposit on the wires, felts, roll covers, doctor blades, hot dryer can surfaces, and calendar rolls. Otherwise known as stickies.
Any person familiar with the process knows how much of a problem this presents. As machine parts and clothing collect stickies over time, the performance of those parts of the machine suffer. Drainage suffers. Dust collects. Profiles deteriorate. Heat transfer diminishes. And the worst manifestation - sheet breaks due to deposited stickies grabbing and tearing the continuous paper web. Stickies can become a real bane on production and present an ongoing challenge to papermakers trying to hit their productivity and quality targets.
The stickies challenge can be tackled many different ways. When papermakers choose to clean and screen the pulp fiber to remove stickies from stock slurries before reaching the head box, their fiber yield suffers dramatically. There are furnish additives like polymers or enzymatic treatment of furnish, which has shown to be effective, except at a very high cost and the need for long dwell time. Other methods include dispersers to treat furnish and break up sticky globs into smaller fragments that tend to stay suspended in the stock or continue on with the sheet after formation. This method requires a significant capital purchase and ongoing use of incremental power from fuel sources. Then there are several high-pressure shower methods to continuously clean clothing, or sophisticated doctoring schemes that clean rolls with high shear and pressure from blades. These reactive methods require a lot of maintenance and upkeep to remain effective.
There are several paper manufacturers that rely solely on recycled fiber sources. Greif is one of them. When their operation in Massillon, OH needed to address the persistent challenge, they chose to look to the far East for solving their stickies problem. Japanese culture is known around the world for their cleanliness and order. Origins for this cultural priority can be traced back to early religious practices and priorities. Cleanliness is about respect for oneself, one's community, and of nature. In more modern times, look no further than Marie Kondo's popularity in the media and entertainment industry. Culturally, they take housekeeping to a whole new level in everything they do, including industrial manufacturing. Toyota, specifically, and 5S in general (Sort, Systematize, Shine, Standardize, Sustain) are all manufacturing methodologies born in the region.
Since Japan is lacking sufficient forests to supply their paper manufacturers with a virgin fiber source, recycling paper is big there, too. Stickies ignore all national borders and show up on hot surfaces and paper machine clothing as they do everywhere else.
How do the papermakers in Japan maintain their machine cleanliness to such an extreme with the same recycled fiber source as in the US? The dominant method is passivation strategies, i.e. preventing deposits and stickies build up, so the problem, which is no longer a problem, ships out with every reel or roll of paper. The leading dryer section passivation company in the Japan region, Maintech, has over 1000 dryer section passivation applications employed. They have taken their chemical and application knowledge across the globe to the rest of Asia, Europe, and now, North America.
Jeffrey Cochran, production manager at the Greif mill in Massillon, says, "The dryer section passivation system from Maintech really works. I've been involved with many chemical trials and technologies over my career, and this one has delivered - exceeding my expectations." The solution employed by the Massillon mill utilized a scanning beam with a traversing head at the first dryer can that applies a mist of passivation chemical directly on the dryer can, hence the name, Dryer Section Passivation (DSP.) The traversing mist nozzle is accurate in its application through patented air curtain technology. The chemistry protects the hot dryer can surface to prevent stickies from ever building up and is FDA-approved. A single application point will utilize the fiber sheet to transfer the chemical effect to subsequent dryer cans downstream. 
Jeffrey continues, "Not only are our early dryer cans shiny again, our dryer felts do not build up stickies either. Dust is no longer a concern. All I have to do is suspend the DSP spraying beam and you will start seeing dust and stickies build up on cans almost immediately."
The application was so successful at this mill, a second beam was placed to apply passivation chemistry directly to the dryer fabric. Then a third beam placed on the paper machine across the aisle. Another Greif mill decided to try the technology on the calender stack just before the reel to prevent buildup. They had to scrape off buildup on the stack nearly every shift. The queen roll now maintains a sticky-free shine without any human intervention.
How does the application pay for itself? Less frequent sheet breaks in the dryer section. Better heat transfer to the sheet, which can lead to steam savings or higher production speeds. Less dust, which presents a fire hazard. Elimination of human labor to clean surfaces regularly. Longer felt and fabric life. More effective felt cleaning from showers. The DSP technology from Maintech has enabled the production team at this mill to focus on other operational priorities.
Papermaking really involves a global community. As one region of the world establishes best practices or new technologies, those ideas quickly spread across other regions of the world. Maintech has been applying their expertise for over 40 years and is in its second generation of leadership. They are ready to invest in applications in North America, where papermakers have been struggling with sticky deposits since the recycling adoption has taken shape.
For more details, please visit Maintech's website at https://maintech-papertech.com/en/dsp/cylinder/index.html
