By Graeme Rodden, Executive Editor, Pulp & Paper International magazine
For its recently-developed HemiForce® agricultural-based enhanced fiber additives, researchers chose that most popular of staples, corn. Ashok Mishra, senior director, global sales and technical services, Enhanced Fiber Additives at Cargill, says the company worked for more than 10 years to develop the patented manufacturing process and the application expertise to commercialize HemiForce in the North American tissue market.
Although there is an obvious green aspect to the product, what with corn being a renewable resource, the main driver for the product is the cost savings it can bring producers, while not losing needed product properties.
In 2009, results at two recycled tissue mills (bath and towel) showed net savings of $8-12/ton for bathroom tissue and $6-12/ton for towel. At the same time, both mills saw improvements in tensile and stretch properties, productivity while reducing fiber use and refining energy. The towel mill was able to reduce the level of wet strength additive it used by 20-25%. Trials with virgin fiber have shown similar results.
How does a kernel of corn improve paper? The HemiForce additives contain a high level of hemicellulose that enhances the cellulose fiber in the furnish and increases the number of hydrogen bonding sites by "building bridges" between the wood fibers.
Besides the advantages mentioned earlier, improved fiber-to-fiber bonding can provide other benefits such as increased machine speed, the ability to increase secondary fiber content and to use lower quality secondary fiber, increased bulk at a higher freeness level and, for tissue producers, reduced dusting during creping, reeling and converting operations.
As well as replacing fiber, HemiForce enhanced fiber additives allow mills to reduce levels of strength and retention aids. Low sheet strength is a long-standing problem with tissue makers. This leads to sheet breaks both in the wet end and in finishing. As more and more mills turn to a secondary fiber furnish, the problem can be exacerbated. HemiForce is designed to alleviate this problem.
As noted there are many "green" elements to the product line in addition to being sourced from renewable agricultural seed fibers and allowing for more recycled content. As a result of benefits such as increased machine speed and the reduction or elimination of refining, tissue makers may reduce energy consumption. By being able to replace chemical additives, a mill will face fewer wastewater issues further downstream. Furthermore, the increased strength provided by HemiForce additives may help lower the basis weight of paper products, helping customers reduce their overall paper use.
Lots of opportunity
Mishra notes that the current focus is on tissue applications in the North American market. There is much interest outside of North America as well with lots of opportunity to grow, says Mishra, but Cargill is taking a strategic approach to how it deploys the product. "We want to firmly establish our North American base before we expand to other geographies."
It is also important to note that only a small part of the kernel is used in the production of the HemiForce additive. In wet milling the kernels are soaked to soften and release their components. The germ is removed for oil; materials in the endosperm are extracted for food, feed and industrial components. It is the fiber in the outer covering (pericarp) that is used to make HemiForce. Mishra likened this part to the small, brown hull-like material in popcorn, the "part that gets stuck in your teeth".
Although HemiForce is being made from corn, with Cargill's ability to access other agricultural seed fibers, Mishra says he expects similar results for other seeds.
The HemiForce additive can be added into the process during stock preparation or in the wet end. Right now, Cargill is focusing on tissue applications, offering grades for both natural (unbleached) tissue and white tissue.
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