白布の紫外線防御効果への素材と織の影響 －透過率・反射率・空隙率およびUPFによる評価－

The ultraviolet radiation (UV) protection efficiency of apparel white fabrics of cotton, nylon and polyester was investigated. The UV protection efficiency depended significantly on the transmittance of their polymer materials. For the cotton and polyester fabrics, the estimated UV protection efficiency showed a strong dependence on the weaving properties such as the type of weave, density of warp and weft, thickness, weight, fabric porosity and surface characteristics. Moreover, ultraviolet protection factor (UPF) of the white fabrics was evaluated for the UV-A and UV-B radiation. The results are summarized as follows: 1) The UV transmittance in the 250-400nm regions of white fabrics of cotton, nylon and polyester depends on that of their material polymers. 2) Polyester is defined as UV-B protective material, because it does not transmit wavelengths shorter than 310nm, and also the reflectance of polyester is lower than that of cotton and nylon in this wavelength regions. 3) The UV protection efficiency of white fabrics of cotton and polyester depends on their weaving properties, especially the type of weave such as plain and twill. 4) Polyester white fabrics with lower porosity than 5% have the higher UPF than 20. 5) The UPF is defined as a UV-B protection factor.