| 摘要 |
PURPOSE:To improve moistureproofness without impairing flexibility by a method wherein polychlorotrifluoroethylene extruded film is uniaxially stretched under the specified conditions and, after that, heat treated in the atmospheric humidity of 80% or more at the temperature, which is not less than stretching temperature and less than melting point. CONSTITUTION:Moistureproof film is produced by uniaxially stretching polychlorotrifluoroethylene (PCTFE) extruded film in the atmospheric humidity of 80% or more by the percent of stretch of 105% or more and, after that, heat-treating in the atmospheric humidity of 80% or more at the temperature, which is not less than stretching temperature and less than melting point. If the percent of stretch is less than 105%, the resultant film is poor in flexibility and crack due to bending or the like develops. Or, if stretching is performed in the atmospheric humidity ms less than 80% and the percent of stretch for giving flexibility to the film is set to be 105% or more, large uneven thickness results and the commercial value of the film is impaired. |
