| abstract |
(57) [Summary] [Purpose] To provide a lightweight polyethylene terephthalate porous fiber which is lightweight, has excellent heat retention and mechanical strength, and has excellent ultraviolet and visible light blocking properties. [Structure] A fiber made of polyethylene terephthalate, which has a dense non-porous layer on the outer periphery of the fiber, has fine pores connected in the fiber axis direction inside the fiber, and has an average diameter (D) of the fine pores. Porosity of 0.1 to 10 μm, including a porous portion having a ratio (L / D) to the length (L) in the fiber axis direction of more than 100, and having a fiber density of 1.30 g / cm 3 or less. Quality lightweight fiber. |