Advanced fibre structure said to offer significant processing and performance advantages

Tokyo – Teijin Group has developed an “eco-friendly” staple polyester nanofibre for reinforcing tires, hoses, belts and other rubber products, the Japanese group announced 11 April.

Converting company Teijin Frontier will start producing the fibre in 2023 and expects sales to reach JPY1 billion (around $8.2 million) by the fiscal year ending in March 2028.

Teijin Frontier aims to “expand the types of polymers that can be used for the new staple nanofibres and continue to develop [applications for] them,” said Teijin.

The new staple nanofibre, 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 optimise rubber reinforcement.

Reinforcing polyester nanofibre, of diameter 400nm or 700nm, 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 nanofibres to be evenly dispersed in the rubber than is possible with conventional fibres, said Teijin.

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

Furthermore, the fibre’s short length prevents entanglement and twisting, and additionally helps to disperse the fibres and rubber evenly, continued Teijin.

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

When used in tires, the nanofibre 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, fibre strength and length is adjust to enable the rubber reinforcement to withstand repeated deformation and abrasion.

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

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