摘要：

551,757. Coating with metals. ALEXANDER. P., CRANSTONE, E. L., and VAPCO, Ltd. Sept. 3, 1941, No. 11279. [Class 82 (ii)] In a process for depositing a film of aluminium or magnesium with a bright surface on a support of paper, material known under the Registered Trade Mark, Cellophane or other moisture absorbent material, the surface of the support on which the metal is to be deposited is exposed to radiant heat in a vacuum for a period less than that required to deprive the material of its moisture content and then, without prolonged exposure of the material to the atmosphere, the deposition of the metal is effected on the surface by thermal evaporation in a vacuum, while preventing the appreciable deposition on the other surfaces of the support. The strip 4, Fig. 1. is wound from a spool 5 on to a spool 6 operated by a clockwork motor 7, both spools being mounted in a chamber 1 which is evacuated through a hole 2. The strip 4 in passing from the spool 5 to the spool 6 is heated by an electric heater 3. The spool 6 is now transferred to a chamber 8 evacuated through a hole 2 and as the strip 4 passes from the spool 6 to the spool 9 it is exposed to the vapour of metal from a wire 12 of such a metal which is fed from a spool 13 of wire through rolls 15 driven by a clockwork motor 14 on to a heater 11 which may be a tungsten rod heated by an electric current. To prevent the vapour from striking the uncovered surface of the material 4, the heater 11 is partially surrounded by a screen 16. A device of the kind described in Specification 513,257, is employed to facilitate maintenance of the vacuum, this device consisting of a plate 17 of aluminium insulated from the chamber 8 by insulators 18 and connected by a wire 19 to a source of electrical high tension. Previous to the starting of the thermal deposition an alternating electrical discharge is maintained for a short time between the plate 17 and an aluminium casing, e.g. the screen 16, surrounding the heater 11. In a modification the chambers 1, 8 are combined in a single vessel divided by a partition, the heated strip passing from the spool 5 past the heater 3 and through a slot in the partition and past the heater 11 and then wound on the spool 9. In a further modification, the coated strip passes through a second slot in the partition on to the spool 9 which is placed in the same compartment as the spool 5. Specification 485,965 also is referred to.

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