| 摘要 |
A method for the production of a cylindrical thermoplastic resin film having a rough inner surface, characterized by preparing a die (5) formed of a mandrel (1) and an external die ring (2) encircling said mandrel and provided therein with an annular resin conduit (3), feeding molten thermoplastic resin cylindrically through a resin discharge outlet (6) the die communicating with the resin conduit while keeping the temperature of at least the portion of the surface of the mandrel separated by not more than 30 mm in the axial direction from the lower end of said resin discharge outlet and confronting said resin conduit at a level 5 DEG to 60 DEG C lower than the temperature of the surface of the external die ring confronting the resin conduit and, at the same time, allowing the interior of the discharged cylindrical resin to retain air therein thereby molding said thermoplastic resin film in a cylindrical shape, and forming on the inside of the cylindrical film a rough face possessing uniform fine rises and falls. |
