This article is part of our series "From mushroom to handbag: Creating a closed loop textile supply chain." Click here to view all articles in the series.
Corn is a superfood — but not one you’ll find in nutrition articles for health benefits. With byproducts like corn syrup, sometimes it’s quite the opposite. But corn’s versatility goes beyond food, and beyond another well-known corn byproduct: ethanol fuel. Its super powers stem from its ability to transform into adhesives, packaging and even clothing, showing up in industrial and apparel textiles.
The industrial connection shouldn’t be surprising, given that Dow Chemical collaborated with Cargill to create a corn-based fiber. The result was Ingeo products, named for "ingredients from the earth," which include fibers used for clothing, bedding and facial wipes, as well as to create 3D printing, plastics, toys and cosmetics cases.
From corn cob to polylactic acid
Ingeo began as a 1989 research project at Cargill by a PhD student trying to create sustainable plastics by using plant carbohydrates from feedstock corn. At the time, the food, agriculture and industrial giant Cargill produced a lot of sugar as a byproduct. The student determined that they could use corn to create polylactic acid (PLA), a biodegradable thermoplastic from renewable agricultural products.
The product, which is 100% bio-based, needs a sugar source to create it. "Today the cheapest source of sugar in the world is corn in the Midwest," said Eamonn Tighe, business development manager for NatureWorks, which produces Ingeo products. "More than 5-10% of the corn produced goes to waste in silos at the end of the season," making it a good candidate to transform waste into new materials.
Cargill scaled up a major commercial biorefinery plant in Blair, Nebraska. In the future, they may open factories in other countries, using different sugar sources. “It’s not about corn; it’s about sugar," Tighe told Supply Chain Dive. "If we put a plant in Asia, likely the sugar source would be sugar cane. If we put a plant in Europe, and we plan to do this, it may be sugar beets. What we need is a cheap sugar source."
How suppliers turn corn into synthetics
Much of the corn NatureWorks uses is grown within 30 miles of the plant, which uses a wet milling process, breaking down the corn into various constituents. About 50% of the corn (the starchy part) is used to make PLA, and the rest is used to make food sweeteners and additives or other products.
They create the lactic acid through fermentation, refining it to make lactide, then it’s polymerized to make PLA. From that they make polymer pellets. These pellets are a raw material supplied to the textile and plastics industry. "We’re an ingredient brand as opposed to a market-facing brand," Tighe said.
Fiber and filament producers buy the pellets, which is typical for textiles. The producers spin it into stable fibers or onto filament yarns and cones on an extrusion line also used for producing polyesters and polypropylenes. The filament producers then supply it to their customers, who can dye or texturize it, or sell it directly to the weaving company.
Thinking beyond the starch
While corn starch products are in the marketplace, researchers are exploring ways to use other corn parts for fiber, as 400 million tons of corn goes to waste each year. Yiqi Yang, a textile chemical engineer and professor at University of Nebraska–Lincoln, is trying to make natural cellulose fibers from corn husks, rather than synthetic fibers from the corn starch.
Using enzymes, alkali and high-temperature water pressure, "we try to modify the fiber’s physical shape to make it more feasible for textile process," Yang told Supply Chain Dive, and that will use less energy and decrease pollution during processing.
The original corn husk fibers are too thick, so he’s trying an environmentally friendly process to extract and split the fibers to make them better for textiles. About 20% of the husk weight is used for fiber, and the remaining 80% can be used to make ethanol, he said.
It’s unclear if this is a viable long-term option, though. It’s tough to hand pick the husks, and machines aren’t yet easily sorting plant parts so the husks can be used. A barrel of corn husks is needed for one sweater, and about 1,000 pounds of corn husks are needed to test the viability of corn husk fiber creation. Scaling up the corn husk fiber business costs money, said Yang.
A pull from downstream in the supply chain
NatureWorks sells more PLA for nonwovens like diapers and wipes, and industrial horticultural fabrics and carpet backing, compared to apparel textiles. Industrial markets are easier because "they tend to be produced on a larger scale and the supply chains are shorter. You deal with two to three levels of supply chain as opposed to seven or eight in the textile chain," said Tighe.
He said the material dyes to brilliant colors and do not fade in the sun, making it good for window blinds. It also has natural fire-retardant properties, a good fit for industrial carpeting. "Our focus the last few years has been to not just sell on sustainability merits but the fundamental property and characteristics relative to other materials," said Tighe.
About 70% of Ingeo products are sold to the food service industry. Walmart helped Ingeo get their start in the early 2000s, buying packaging materials like food containers. "As a relatively small company with one big factory, we had to focus on areas that could bring volume quickly," he said.
"The brand or retailer deciding they want to work with these types of materials ultimately are the ones with a significant amount of power."
Business Development Manager, NatureWorks
Ingeo fibers attract interest because major retailers feel an obligation to use sustainable materials and may be interested in bringing a new product to market. "There’s an anti-plastic rhetoric out there in the moment, especially across Europe," Tighe said. "That means we’re often talking to a downstream brand, linking together the supply chain," he said. "We spend a lot of time talking to companies several levels downstream."
Sometimes NatureWorks connects the dots, and sometimes the brands bring them in to talk to their current suppliers. “It often ends up being a pull by the brand. The brand or retailer deciding they want to work with these types of materials ultimately are the ones with a significant amount of power,” he said. "They’re the customer, so the supply chain replies to what the customer requires."
One major issue is that Ingeo has a 170 degree melting point, so it can’t be ironed. "That has been a challenge in taking it into many mainstream textile areas," he said. To increase the melting point, they need to create different products. "That’s probably the primary reason we haven’t focused on textiles."
Scaling up beyond the 'early days'
The Ingeo business grew 12% last year. The Nebraska factory has a capacity of 350 million pounds per year. It’s currently at 85% capacity, and NatureWorks is considering where to open another factory.
In the textile area, NatureWorks is developing woven tea bags and coffee filters. "There’s lots of outcry about single use coffee capsules," he said. An Ingeo filter or pod can be composted along with the grounds.
"I’d argue we’re very much still in early days. Most other textile fibers out there were developed many decades ago," he said. "There’s still a lot of development work to do." The fibers need some optimization to use in the factories. "It’s a little like if you normally eat rice, and then decide to eat pasta."