Abstract: A seat belt webbing in which elongation at initial yield point is 6% or less, tenacity at 8% elongation is 1.5 to 7 kN, tenacity at break is 15 kN or more, elongation under load of 11.1 kN is 10 to 40% and an energy absorption work amount is 600 J/m or more, and a passenger-holding device comprising the seat belt webbing and a seat belt retractor portion having a lock mechanism for stopping rotation of a take-up shaft in response to acceleration or abrupt unwinding of a webbing exhibits high energy absorption performance at low costs.

Abstract: A high-strength ultra-fine fiber construction including a high-strength multi-filament yarn including ultra-fine filaments of a fineness of a single filament less than 0.8 denier, a tenacity of 6.5 g/d or more, and the elongation at break of the multi-filament yarn being 15% or more. In order to obtain such a fiber construction, islands-in-sea-type or divisional type conjugate spinning is initially carried out to obtain conjugate multi-filament yarns, which is subjected to weaving to produce a fabric, and a island component removing or dividing treatment is finally done in order to obtain the high-strength ultra-fine fiber in the fiber structure.Ultra-fine fibers of the desired strength together with a particular range of a cover factor provides all the advantages of the ultra-fine fibers. A reduced air permeability, when it is necessary, can be easily obtained. Namely, a desired mechanical property as well as a desired softness are both obtained, while the number of naps and filament breakages are reduced.