Teijin reinforces tires, rubber goods with eco-friendly nanofiber

TOKYO—Teijin Ltd. has developed an eco-friendly staple polyester nanofiber for reinforcing tires, hoses, belts and other rubber products.

Converting company Teijin Frontier Co. Ltd. will start producing the fiber in 2023 and expects sales to reach around $8.2 million by the fiscal year ending in March 2028, the Japanese group said in an April 11 news release.

Teijin Frontier aims to "expand the types of polymers that can be used for the new staple nanofibers and continue to develop (applications for) them," said Teijin.

The new staple nanofiber, it noted, incorporates both polyester nanofiber and polyethylene polymers, within Teijin Frontier's proprietary "sea-island" composite cross-section.

According to the Tokyo-based group, different polymers can be used for the "sea" and "island" parts of the structure to optimize rubber reinforcement.

Reinforcing polyester nanofiber, of diameter 400 nanometers or 700 nanometers, is used as the island, while the surrounding sea part is made with polyethylene, which mixes readily with rubber.

Mixing takes place at the molecular level, which enables thousands of times more nanofibers to be evenly dispersed in the rubber than is possible with conventional fibers, said Teijin.

The length of the new staple nanofiber is just 1 millimeter or less, but the aspect ratio is high thanks to the small diameter, which contributes to reinforcement, the group added.

The fiber's short length prevents entanglement and twisting and helps to disperse the fibers and rubber evenly, continued Teijin.

It forms continuous surfaces, rather than dispersed clumps, that effectively absorb deformation stresses, resulting in more durable products.

When used in tires, the nanofiber is said to increase elasticity and reduce rolling resistance, thereby improving fuel efficiency and reducing noise.

Teijin further claimed that the product can improve the elastic modulus and durability of automotive hoses and belts, which has been difficult to achieve until now.

Conventionally, fiber strength and length adjust to enable the rubber reinforcement to withstand repeated deformation and abrasion.

Increased length, however, leads to entanglement and twisting when the fiber is kneaded into the rubber, which reduces strength due to less efficient fiber dispersal.

Teijin claims such problems are avoided with its newly developed staple nanofiber.