| 摘要 |
PURPOSE:To ensure that an excellent cast film free from air bubble entrainment by adjusting the moisture content of polysulphone resin solution to a level of 2wt.% max and thereby improving wettability to a support during casting. CONSTITUTION:A polysulphone resin solution 3 is cast to a support consisting of a stainless belt 1 by a comma roll 5, and thus a polysulphone resin film is formed. This solution 3 is adjusted by a molecular sieve so that the moisture content is reduced to 0.2wt.%. Consequently, wettability to a belt 1 is improved and air 2 is no longer entrained so that a bubble nucleus 4 is not formed. Therefore, the thickness accuracy of the film obtained by peeling it off after drying is enhanced, and the polysulphone resin film has superior smoothness, high transparency and satisfactory appearance. |
