Fiber having optical interference function and use thereof

A fibrous structure having an improved function of optical-interference, characterized in that said fibrous structure contains flat optically interfering filaments which are formed by alternately laminating individually independent layers of polymers having different refractive indices in parallel with the major axis direction of a flat cross section, wherein (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 coating layer of a polymer is formed on at least the surface of said optically interfering filaments, a refractive index of said polymer being lower than the refractive index of a polymer which constitutes said optically interfering filaments and has a highest refractive index.

A multi-filament yarn characterized in that the multi-filament yarn

• (1) comprises, as a constituent unit, flat optically interfering filaments which are formed by alternately laminating individually independent layers of polymers having different refractive indices in parallel with the major axis direction of the flat cross section, wherein (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,
• (2) the constituent filaments having a flattening ratio in the range of 4.0 to 15.0, and
• (3) the multi-filament yarn having an elongation at break in the range of 10 to 50%.

A multi-filament yarn having an optical-interference function of producing different colors, which comprises, as a constituent unit, flat optically interfering filaments which are formed by alternately laminating individually independent layers of polymers having different refractive indices in parallel with the major axis direction of the 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, said multi-filament yarn exhibiting the color development of different colors along the lengthwise direction thereof and/or among the filaments.

A multi-filament yarn having an improved function of optical interference, comprising, as a constituent unit, flat optically interfering filaments which are formed by alternately laminating individually independent layers of polymers having different refractive indices in parallel with the major axis direction of the 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, the filaments being imparted with an axial twist in the lengthwise direction thereof.

A float textile having a function of optical interference, characterized in that said textile contains, as a warp and/or weft, a texture construction of at least two float components formed of a multi-filament yarn comprising, as a constituent unit, flat optically interfering filaments which are formed by alternately laminating individually independent layers of polymers having different refractive indices in parallel with the major axis direction of the flat cross section, wherein (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.

An embroidery fabric, characterized in that said fabric is prepared by embroidering a substrate cloth with a multi-filament yarn, as an embroidery yarn, comprising, as a constituent unit, flat optically interfering filaments which are formed by alternately laminating individually independent layers of polymers having different refractive indices in parallel with the major axis direction of the flat cross section, wherein (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, the stacking number of the filaments constituting the embroidery yarn stacked in the direction intersecting at right angles the substrate cloth being 2 to 80.

A composite yarn comprised of a high-shrinkable yarn and a low-shrinkable yarn, characterized in that the low-shrinkable yarn is comprised of flat optically interfering filaments which are formed by alternately laminating individually independent layers of polymers having different refractive indices in parallel with the major axis direction of a flat cross section, wherein (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.

A differently brightening non-woven fabric, characterized in that said non-woven fabric is obtained by randomly and collectively stacking flat optically interfering filaments in a state where the filaments are axially twisted at intervals along the lengthwise direction thereof, the flat filaments being formed by alternately laminating individually independent layers of polymers having different refractive indices in parallel with the major axis direction of a flat cross section, wherein (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.