| abstract |
A flat optical-interference-functional fiber formed by alternately laminating individually independent layers of polymers having different refractive indices in parallel with the major axis direction of its flat cross section, characterized in that (a) the ratio (SP ratio) of the solubility parameter value (SP1) of high refractive index polymer to the solubility parameter value (SP2) of low refractive index polymer is in the range of 0.8<=SP1/SP2<=1.1, and a fibrous structure using the fiber. According to the present invention, there are provided a fiber which has high color development intensity based on optical interference and forms clear color; and a fibrous structure thereof. |