| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical sheet having a multilayer structure with a light diffusion layer at a surface layer, capable of enhancing a concealment property of a back face shape, and making light incident from a light source to reach a depth by increasing a thickness ratio from an incident end face to an opposite end face a surface layer, and also enhancing utilization efficiency of light incident from the light source.SOLUTION: An optical sheet includes a transparent thermoplastic resin sheet having a three-layer configuration consisting of a surface layer, a center layer and a back layer, or a transparent thermoplastic resin sheet having a two-layer configuration consisting of a surface layer and a back layer. The surface layer is manufactured by an extrusion method that extrudes the resin from a T die, using a resin with a higher MI value so that the surface layer has higher viscosity than another layer, or setting an extrusion condition so that the surface layer has lower resin viscosity than another layer. The thickness ratio of the surface layer is gradient. |
