Trinseo: Innovation a key to sustainable tires

BERWYN, Pa.—Sustainability as an industry is a growing demand for tire producers.

And a more sustainable tire industry starts with better building materials and collaboration, said Sandra Hofman, director of technology and innovation, synthetic rubber, for Trinseo.

"I think at the moment we're seeing this big wave hitting us. We see that the auto industry is changing," Hofman said. "I think the chemical industry has this big challenge as well."

For Hofman, hearing what customers are demanding, the concept of sustainability that uses all four Rs (reduce, reuse, recycle and renew) is becoming more important.

"As a company, we have to find solutions. For me actually, it's like if you're taking the Magic Triangle: Yes, we can work on the performance, and this has obviously been our focus, but now also we can take sustainability into account," she said. "This is not only how the tires are performing but also what they are made out of. For us, the raw material base becomes extremely important."

As a synthetic rubber manufacturer, Trinseo is looking for bio-based materials to bring more renewable content into its polymers, she said. A key raw material for Trinseo is styrene monomer, a large portion of which is used in packaging applications. The firm is part of a joint industry initiative called Styrenic Circular Solutions, which aims to drive the recycling of polystyrene back into new styrene monomer in the future of the industry. Since polystyrene can be depolymerized in high heat back into styrene monomer, it is "infinitely recyclable." That new styrene monomer would then be recycled material.

"For us this is an extremely interesting concept, also to use such recycled styrene monomers in an SSBR as a recycled content," Hofman said. "Therefore we can also help our customers to actually hit their targets for allowing recycled for recycled content in a tire eventually. And they don't have to change the paradigm because we are still delivering a performance polymer SSBR. They don't have to change the way they're mixing. We are basically having a building block you could say from an alternative source."

Expanding efficiencies

Lower rolling resistance is another angle as a familiar sustainability goal for tire producers, and a way SSBRs such as Trinseo's recently released SSBR 918S can contribute, Hofman said. While tires need to have a high level of safety and performance, it's also important to reach a level of energy efficiency in line with legislation requirements.

"There's only one direction when it comes to (carbon dioxide) emissions," she said. "This is basically just going down."

In applying multi-functionalization technology in its SSBR 918S, Trinseo was able to improve performance on two of the points of the Magic Triangle without sacrificing the third, she said.

"We actually have managed to keep abrasion resistance at the level of the previous generation of products, but at the same time we are improving on the wet grip but also substantially improving on rolling resistance," Hofman said. "You could say we're making our tires safer, and we are also making them more sustainable."

The key is controlling the interaction of the polymer with the filler, to reduce the hysteresis which translates into the energy savings of reduced rolling resistance, she said. One downside to working on functionalization is that a polymer might provide a challenge in processability, but that isn't an issue in this case.

"It's not only a design feature to further expand the Magic Triangle with respect to grip and with respect to rolling resistance while not sacrificing abrasion, but also to secure that the compounds are actually easy to process," she said. "It's really the combination of those four features which makes our product more interesting."

For Hofman, contributing to rolling resistance helps offset when a tire's greatest level of emissions of greenhouse gases is in its use phase. A tire can produce more than 90 percent of its emissions during use, as opposed to about 3 percent through its raw materials and about 2.5 in manufacturing, she said. Using data from tire manufacturers, over the lifetime of a set of tires, Trinseo's SSBRs save about 26 gallons of fuel through reduced rolling resistance compared to the previous generation of tires, translating into a larger reduction of CO2 emissions.

More efficient tires are important particularly as the larger automotive industry shifts toward e-mobility, as batteries mean a higher weight for the cars, she said. A higher overall weight means more abrasion, in addition to a higher torque with electric engines.

"The problem with the heavier cars is the increased level of abrasion that you're going to find," she said. "That's already what we're working on, more abrasion-resistant polymers while also exercising the performance."

Future collaboration

Technology like abrasion-resistant polymers are coming in the short term, while concepts like bio-based raw materials are a little farther off, she said. But both approaches are important, as alternatives to rubber tires aren't likely to show up anytime soon."I think rubber materials as we use them, I think we will have them for quite some time," she said. "We're still running on air tires. I'm not sure about 20, 30 or 50 years down the road. But for the moment, this is critically important."

Trinseo is part of a joint venture leading to Regenyx L.L.C., a producer of the recycled polystyrene into styrene monomer. Regenyx, formed in April from Trinseo's JV with Chevron Phillips Chemical Co. L.P., AmSty and Agilyx, runs a Tigard, Ore., facility producing about 10 metric tons of the material per day, according to a Trinseo news release. The firm is planning to develop a larger facility scaled to 50 tons per day with a focus on the West Coast of the U.S.

"As a company, we need to see how basically we can contribute to the future, to a circular economy," Hofman said. "Therefore, we have to not only make the product, but consider how we can contribute to the recycling of the materials.

"This is where the industry is moving to in the future. You see that competitors are working together because the size of the problem is just massive," she said."

Cokoon, the new open-source sustainable adhesive technology developed by Continental A.G. and Kordsa Technik Teksil A.S. to eliminate the need for resorcinol and formaldehyde, is an example of that type of collaboration, she said.

"I think collaboration is extremely important," she said. "I think we are going to see more and more alliances, working with customers, working with other partners in the value chain, opening up and working with institutions. And then also we need to have showcases and demonstrations, and reaching out to who are the right engineering partners. Collaboration is a key for what we are heading into."

As change approaches the tire industry, it's important for developers and manufacturers to be active and responding quickly to challenges, even though things usually take more time in the tire industry, she said. Working with customers very early on in product development means bringing them into the product development cycle, showcasing and demonstrating, and supplying pilot quantities of modern materials to test.

"It's happening right now. It's coming fast, and speed to market is critical," she said. "That's a little bit of a contradiction with the tire industry, at least the tire industry from not too long ago. In order to be able to respond to all those changes in the market, we need to include and support our customers so that they are also faster in implementing new materials, and that will again require collaboration."