| 摘要 |
1,270,442. Tubular laminated films. PIERSON INDUSTRIES Inc. 19 May, 1969 [20 May, 1968; 1 May, 1969], No. 25341/69. Heading B5B. Laminated films having plies of at least two different thermoplastic materials are extruded from a blown tubular die, which comprises a die head assembly mounted for rotation on a supporting die holder 36, the molten thermoplastic materials being conducted in separate flows from their respective extruders through adapters 26, 27, through passages 37, 38, 39 in the die holder 36, and into concentric annular chambers 55, 58, 59 in the die head to form tubular film plies which are united at a common internal orifice 71 before extrusion, the die head being rotated to remove irregularities in the film, and the molten materials being distributed from the die holder into the die head by annular reservoirs formed at the interface thereof. The die head assembly comprises three (as shown) concentric mandrels 40, 60, 61 (Figs. 3 and 4, not shown) and a ring 62 which define therebetween the annular chambers 55, 58, 59, the base-plates of the mandrels having passages through which the chambers communicate with the annular reservoirs and die holder passages, and the stems of the mandrels having spiral formations to homogenize the molten material. As shown, two different materials are used; one or three materials may be used with suitable adapters, as in Figs. 7 and 8 (not shown). Air is blown into the extruded tubular film through a port 107 in the innermost mandrel, and an external, circumferential, inwardly-directed air stream is provided by a rotating air ring (Fig. 1, not shown). Finally the tubular film is flattened between two inclined conveyer belts (Fig. 5, not shown) passing at one end round two nip rolls. In an example, nylon and polyethylene are used as film-forming materials.
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