In 1996, TOYOBO launched high resilience three-dimensional network structured fiber material “BREATHAIR TM” to cushion market. BREATHAIR TM has following characteristics: high resilience, high breathability, easy to wash and recyclable because of its 3D structure and thermoplastic raw materials. On the other hand, polyurethane foam has wide range of products from high resilience to low resilience, especially low resilience foam is widely used as higher quality materials for various usage. 　 Though it is also required low resilience performance for 3D network structured fiber material recently, that is difficult issue from points of view of resilient performance and durability by using thermoplastic raw materials. To overcome its dilemma, it was necessary to design properly not only polymer structure but also fiber structure. After 10 years’ R&D period, we finally succeeded to develop the low-resilience 3D network structured fiber material with superior durability.