| 摘要 |
1,236,585. Extruding transparent or translucent thermoplastics. BRITISH CELANESE Ltd. 10 Oct., 1968 [11 Oct., 1967], No. 46403/67. Heading B5A. Transparent or translucent optically patterned thermoplastics material is made by passing a first thermoplastics material from barrel 2 through perforations 13, 14 and slots 10-12 in a plate 3, and intermittently injecting a second, optically distinct, thermoplastics material from a barrel 7 via conduit 15 to perforations 13, 14. Flow of the first material through perforations 13, 14 is interrupted during injection, strands of the second material being extruded between layers of the first material from slots 10-12, the total flow being constricted to form an integral laminar-like product during passage through a nozzle 4 and die orifice 5. After each injection step, perforations 14, 15 are purged by the first material. Thermoplastics mentioned are polyvinyl chloride, polystyrene, vinyl chloride / vinyl acetate copolymers and secondary cellulose acetate, the latter being preferred. Also, preferably, the first and second materials are identical polymerically the optical difference being due to, e.g. dulling agents, dyes, pigments and fluorescent additives. The extrusion product may be granulated and the material generally may be used in spectacle frames, combs, and decorative panels for walls or floors.
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