| 摘要 |
<p>PURPOSE:To obtain a printing film capable of the restraint of dimensional change after printing and suitable for dimensional accuracy required to a switch mechanism by a method wherein a coextrusion is carried out by two-layer structure of thermoplastic polyurethane and polyamide resin which are provided with specified optical properties and the surface of polyurethane is worked so that is takes a specified roughness. CONSTITUTION:Both surfaces of the polyurethane sheet 2 used is smoothed. When the thickness of the sheet is set to 150-200mum, the total optical transmission exceeds 70% and the optical transmission in a wave length rnage under 360nm is 0%. Just after the coextrusion with polyamide resin 3, the surface 1 of thermoplastic polyurethane 2 is matted or satinized, the average roughness at the center line of the surface is given by 0.5-50mum. The polyamide resin used should be selected according to the fluidity of thermoplastic polyurethane to be coextruded. 6-nylon, 6.6-nylon, 6.10-nylon, 11-nylon, 12-nylon, etc. are used and polyamide resin having a low melting point is desirable in molding.</p> |
