| 摘要 |
982,758. Laminates and laminating. ST. REGIS PAPER CO. Feb. 15, 1961 [March 16, 1960], No. 32062/64. Divided out of 982,757. Heading B5N. [Also in Division D1] A method of coating a porous web 37, e.g. paper or woven or unwoven fabric, with a thermoplastic resin, e.g. polythene, a polyamide, a formaldehyde polymer, superpolyoxymethylene, or polypropylene, comprises drawing and stretching through an air gap from an orifice of a sheet extrusion die 33 a molten film 35 of the resin, by movement of the web past a coating zone where the film 35 contacts one side of the web, and applying suction at the other side to suck the film into the web. Suction is applied by a stationary chamber 29 connected to a suction pump 31 and located within a suction roll 25. Heaters 27a may control the temperature of the zone, and the web 37 may pass round a pre-heating roll 36 or be heated radiantly. One or both walls of the chamber 29 may be angularly movable, e.g. to 29c, see Fig. 5 (not shown). The coated web is passed around a cooling roll 27, is trimmed, if necessary, by disc knives 42, and passes to a wind-up roll. In a modification, Fig. 8, the web 68 passes over a stationary suction-box 60, an endless carrier screen 61 passing between the web and the box. A fixed perforated screen may replace the moving screen 61. In a modification of the apparatus of Fig. 8, see Fig. 10 (not shown), the suction box comprises two chambers in series, the extruder being located at a point between the two chambers. Slightly modified apparatus are described employing a suction-box, Fig. 11 (not shown), and suction rolls, Figs. 12, 14 (not shown), in which a layer of scrim is attached to a web of paper by the resin which overlies both, see Fig. 16 (not shown), the paper and the scrim being led past the extruder which deposits molten resin on the scrim. It is stated that the apparatus may be employed to produce a laminate in which the scrim is intermediate two paper webs, the lower surface of the upper web having the resin film applied thereto, see Figs. 17, 18 (not shown). The web 37 may be the same material as the coating, and may be perforated by a high voltage arc. Where adhesion of the coating would be assisted by oxidation the spacing between the extrusion nozzle and the coating zone may be increased. |
