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On-site Generation of Dry Strength: A Sustainability Story

On-site generation of chemicals, including dry strength additives, can help papermakers stay competitive while reducing their carbon footprint.

By: Christophe Zebst | December 14, 2021 | Reading time: 5 minutes

As world leaders and other government representatives met in November at the 26th Conference of the Parties (COP), COP26, in Glasgow, and agreed to the new climate commitments, the world was again reminded of the urgency of sustainable solutions to tackle climate change.

At Solenis, we continually strive to improve the sustainability of our products while enhancing their performance. For decades, Solenis has been developing and offering chemistries that can be manufactured at the mill site, reducing shipping and handling costs. These kinds of solutions are widespread in our portfolio.

With the rippling effects of the global pandemic and turmoil in raw material supply chains and transportation, Solenis products made via on-site processes are making a difference and helping customers deal with multiple challenges. It is particularly true for on-site strength additives, which offer several advantages to mills looking to balance productivity and profitability goals with increasingly aggressive sustainability initiatives. In this post, we review the impact of the pandemic on fiber supply and quality and how an on-site generation of strength chemistry can address issues on several fronts.

The Right Chemistry

is necessary to address issues in deteriorating fiber quality


is a major sustainability target for the containerboard industry

Dry-Strength Additives

activated on site can reduce a mill’s carbon footprint

COVID-19, Paper and Packaging

During the COVID-19 outbreak, as the world moved online and became more remote, e-commerce boomed, sending the demand for paper packaging to unprecedented levels. Even though the economy is recovering, this demand is not slowing down. E-commerce is here to stay as the main driver for future growth in packaging.

This trend is impacting the supply of fibers and, as a result, paper strength has emerged as a primary concern. Traditionally, papermakers have several levers that they can pull to improve strength: the furnish type, addition of starch, increase in basis weight, and refining of fibers. Let’s review each to understand the interplay of pandemic forces and various papermaking activities.

Furnish Type — One direct result of the pandemic can be seen in the availability and quality of recycled fibers in the supply chain. For instance, school closures during 2020 and 2021, combined with permanent work-from-home policies adopted by many companies, have decreased the volume of general office wastepaper entering the recycling stream. It means reduced quantity and quality of recycled fiber Solenis customers depend on for producing cardboard and paperboard packaging.

Starch Consumption — Starch has been used in the paper industry for decades to compensate for the poor mechanical properties of wastepaper, but recently, the use of starch has been accelerated. At higher addition levels, starch plateaus and presents papermakers with increasing technical problems. These include increased microbiological growth requiring biocides, increased drying requirements, and decreased machine output, ultimately reducing the sustainability of the paper mill.

Basis Weight — Often, papermakers produce stronger paper by increasing the sheet basis weight. It effectively means that the amount of fiber in the paper is higher, which is neither a cost-effective nor a sustainable solution.

Refining — Refining involves the mechanical treatment and modification of the pulp fibers, which has the effect of increasing the surface area on a given fiber to improve bonding and therefore strengthening potential. Unfortunately, with reduced quality and quantity of incoming fiber, the effect of refining becomes less pronounced. Paper fibers can only be refined a limited number of times until the benefits are severely diminished. In addition, the energy required for the refining process is very high and a side effect of this process is to reduce the dewatering capability on the machine, resulting in an increased drying energy requirement and potentially reduced machine output.

While the above options can certainly improve paper strength, each brings associated economic and sustainability problems. With the ever-increasing market demand for packaging combined with reduced fiber quality and availability, the sustainable solution seems to be reduced basis weight, also known as light-weighting. Unfortunately, light-weighting leads to weaker packaging and increases the risk of goods being damaged in transit.

As such, to make light-weighting possible while retaining the functionality of the box, papermakers rely on dry strength additives to improve paper strength properties and compensate for the strength loss. For example, Hercobond™ Plus, a Solenis on-site generated dry-strength additive, enhances the end-use performance of a variety of paper and paperboard packaging grades. Unlike other dry-strength additives, Hercobond Plus is not a solution polymer but a microparticle that is built on a unique, high-molecular-weight polyacrylamide (PAM) foundation.

The resulting microparticle is easily retained within the fiber network, providing increased strength through covalent bonding. The microparticle structure is much larger than a soluble polymer and results in improved retention on the fibers and an improved direct strength performance. In addition, the structure of the microparticle suppresses the effects of wet-end contaminants, such as soluble lignin and anionic trash, which generally tend to reduce the effectiveness of polymeric additives. This leads to a flexible technology that is effective over a broad range of furnishes, including 100% recycled, virgin kraft, and high-yield corrugated medium pulps.

By increasing strength and reducing basis weight Hercobond Plus helps manufacturers meet the growing demand for reduced basis weight packaging, even when using poorer quality fiber, and often at improved production output. This benefits not only the specific manufacturers but also the entire value chain and the packaging industry in general.

Hercobond Plus Technology: Improving Sustainability

Traditionally, dry strength additives are produced in chemical plants and shipped at relatively low solids content to paper mills due to issues with performance and shelf life. As a result, chemical suppliers end up shipping huge quantities of water to their customers.

Hercobond Plus is produced through a patented process at the paper mill site, rather than in a chemical plant. This has the distinct advantage that the raw materials used to make the product can be delivered at significantly higher active solids. The process uses a unique, high molecular weight polyacrylamide (PAM), which is activated to create highly cellulose-reactive aldehyde groups that lead to powerful strengthening performance.

Dry strength additives activated on-site reduce the carbon footprint of the packaging produced. Shipping the components for on-site processing reduces handling and shipping costs and allows the product to be tailored specifically to meet each customer’s requirements.

With the current supply chain bottlenecks and limited availability of trucks for carrying freight, on-site polymer activation offers the added advantage of supply reliability. Compared with conventional alternatives, products like Hercobond have a longer shelf life with less waste, 20% performance improvement, 60% reduced freight cost, and delivery frequency.

To learn more about how Hercobond Plus dry strength additives can be tailored to your mill’s unique needs, improve performance, and lower costs, all while increasing overall sustainability, contact a Solenis expert today.

Christophe Zebst

Global Marketing Director, Packaging and Graphics & Specialty Papers

Christophe joined Solenis during the transfer of BASF wet-end paper and water chemicals business to Solenis. At BASF, he worked in sales, application, product management and marketing. At Solenis, he is very focused on market needs and strives to support customers by offering innovative and sustainable solutions. In his free time, he likes to recharge by spending time outside on nature walks and he is also a keen sportsman.