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Asics designed a sneaker that’s made to be torn apart

White polyester and special glue allow the Nimbus Mirai to be recycled into new running shoes.

Asics' Nimbus Mirai contains recycled polyester that's built to be recycled, too.

Asics' Nimbus Mirai contains recycled polyester that's built to be recycled, too. Credit: GreenBiz/Sophia Davirro

Asics launched a shoe in mid-April that’s simple to rip apart and recycle into new footwear. 

The upper part of the $180 Nimbus Mirai is made from a single type of polyester, instead of multiple materials in complex layers. It’s glued to the sole with a custom-made adhesive that detaches when heated, making the shoe easy to break down into its raw materials.

Shoes are notoriously difficult to recycle. A typical pair of sneakers has dozens of blended components including adhesives, hard plastic or metal eyelets, trims and springy polyurethane foam. Flashy dyes and pigments add further complexity. They’re hard to dismantle and logistically difficult to recycle. 

"Footwear composition and its layered construction are highly complex, which only makes achieving recyclability more difficult," said Tiffany Hua, an analyst at Lux Research. "Moreover, each footwear type and style — athletic shoes, sneakers, flats, dress shoes, boots, sandals — has its own intricacies to consider."

Yet shoemakers pump out nearly 24 billion pairs of footwear globally each year, according to Statista. Two-thirds of all apparel lands in a dump or incinerator. The footwear industry emits 1.4 percent of the world’s greenhouse gases, according to a 2019 analysis by Quantis

Asics is hoping that 100 percent of its products will be made from recycled material by 2030, and that the company will hit net zero two decades after that. The brand currently uses more than 30 percent recycled polyester in its footwear and has recycled ingredients in 95 percent of all its shoes, it says.

The rings, called aglets, around sneaker shoelace holes are typically metal or hard plastic. On the Nimbus Mirai, they are made of soft polyester fiber to ease the recycling process.

The rings, called aglets, around sneaker shoelace holes are typically metal or hard plastic. On the Nimbus Mirai, they are made of soft polyester fiber to ease the recycling process. Credit: GreenBiz

Tearing shoes apart at high temperatures

Nimbus Mirai shoes are 87.3 percent recyclable, Asics says. Twenty-four percent of the cushioned midsole includes renewable materials, including sugar cane processing waste.

Each pair carries a QR code on the tongue which instructs consumers to bring old pairs to an Asics store or mail them within the U.S., Canada, U.K., Netherlands, France, Japan, Australia or New Zealand.

The used shoes will be taken in by Terracycle, Asics’ recycling partner. The Trenton, N.J., company has tackled hard-to-recycle items such as cigarette butts, wine corks and baby food pouches since 2001.

Terracycle will heat each sneaker, at temperatures higher than in a conventional oven, to weaken the custom adhesive, then pry apart the sole from the upper.

The soles will get turned into pellets and shipped back to Asics to become signage and floor mats at retail stores, according to Terracycle.

The uppers are shredded and washed. "The pieces are then brought through a solvent-based recycling process consisting of multiple steps of washing, dissolution, filtration, precipitation, and drying to recover high-quality purified polyester material in powder format," Hua Liu, the company’s VP of research and development, wrote via email.

The polyester powder is then turned into pellets, the pellets will be spun into fiber, creating yarn, and the yarn will be knitted into the upper fabric of — a brand new pair of Nimbus Mirai sneakers.

The lack of color helps the Asics Nimbus Mirai with recyclability.

The lack of color helps the Asics Nimbus Mirai with recyclability. Credit: GreenBiz

"Terracycle’s R&D department developed a closed-loop disassembly and recycling process that allows all parts of the shoe, from shoelaces to sole, to be recovered and recycled," Liu said. "As brands design products with end-of-life in mind, it is critical to account for waste management infrastructure and plan for necessary investments and collaborations."

The company has previously experimented with textile waste recycling and low-water and low-carbon dyeing processes. Its circular practices include reselling returned shoes to consumers at a discount.

"We are very confident that its focus on circularity will help inform how best to integrate [the] recycling process and make better decisions in future product development to further reduce the CO2 emissions across even more of our products," Gentaro Makinoda, Asics’ global innovations communications manager, told GreenBiz via email.

A small club including Puma and Nike

Asics joins a small club of sneaker makers designing for circularity. On’s recyclable Cloudneo shoe debuted in 2022. Salomon’s Index.01 and Nike’s ISPA Link Axis, launched in 2021. 

Puma recently experimented with a suede shoe that it broke down into compost for farming.

And Dr. Martens now has a program for reselling used shoes.

[Continue learning about circular business models and materials at Circularity 24 — the leading conference for professionals building the circular economy — taking place in Chicago, IL, May 22-24.]

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