| 摘要 |
1297465 Making tubular films POLYMER PROCESSING RESEARCH INSTITUTE Ltd 28 May 1971 [8 June 1970] 18061/71 Heading B5B Tubular film is made by downwardly extruding a polymer melt or solution from annular orifice 2 and passing the film in contact with cylindrical net 12 through reduced-pressure chamber 4 in a coagulation or quenching step, prior to flattening and wind-up. The coagulant or quenching liquid is allowed to flow down the net and in contact with the film from reservoir 5 surrounding the film, and air-tight seals are maintained by means of the coagulant at the entry and exit points to the chamber, e.g. liquid seal 6 and sponge 22, 23. The net, whose tension is adjustable, e.g. by ring 18, extends out of the bottom of the chamber, but need not extend out of the top. As shown, the entry to the chamber comprises two rings 13, 14 whose inner surfaces bear inclined grooves 42 and which also define an annular groove 45 at their meeting point. A plurality of weirs 30, 301 and a diameter control ring or rings 33 may be provided to control coagulation and net diameter respectively. Coagulant may also be supplied internally to the tube. In examples, melts of polyethylene, polypropylene, polystyrene, P.V.C., nylon or polyester, or solutions of P.V.A., P.A.N. or a P.A.N.-P.V.C. copolymer are used. During extrusion the conditions are adjusted to obtain a wrinkle free product. |
