| 摘要 |
1467033 Laminates BELOIT CORP 17 May 1974 [11 June 1973] 22082/74 Headings B5A B5B and B5N A multilayer sheet material suitable for use in packaging is produced by combining together a substrate and two layers of thermoplastics material, the thermoplastics material for one of the layers being heated, before the layers are combined, to a high enough temperature to oxidize its resin and the thermoplastics material for the other layer being heated to a lower temperature below the oxidation temperature of its resin, the layer of higher temperature material then being disposed between the substrate and the layer of lower temperature material so that the odour of the higher temperature layer is contained by the substrate and the lower temperature layer. The thermoplastics material may be polyethylene, polypropylene, a modified polyethylene or ionomer and the substrate may be paper or an extruded film which may be heated to the temperature of the lower temperature layer. The higher temperature material may be heated to 620- 650‹ F. and the lower temperature material to 520-580‹ F. The multilayer sheet material may be made using apparatus comprising an extruder 11, metering valve 12, flow divider valve 13, dual slot extruder die 15, means 72 to heat one of the divided streams to a temperature high enough to oxidize the resin, means 73 to heat the other stream to a lower temperature and means 17, 20 to combine the two extruded layers 18, 19 with the substrate 16, the flow divider valve comprising a valve body 25 having an inlet 30 therein and spaced outlets for connection with insets of the dual slot extruder die, a passageway 31 in the valve body leading at right angles with respect to the inlet, a flow divider 41 slidably guided in the passageway and having a peak 44 positionable in alignment with the centre line of the inlet to equally divide the flow of hot melt thermoplastics material and means 45 for adjustably moving the flow divider along the passageway to proportion the flow of the material to the outlets. Hot plastics material passing from passageways 32, 33 may be further heated by heaters 70, 71 circling adapters 63, 65. In a modification of the apparatus the material to be heated to the higher temperature is passed through a heat exchanger associated with one of the outlets leading from the valve body, the heat exchanger comprising an elongated block having an elongated loop-like circuitous path extending along it and containing at least one melt mixer therein, and heating blocks extending along opposite sides of the block. |
