GB1008203A - Coating continuous materal - Google Patents

Abstract

1,008,203. Web and filament coating apparatus. INDEVCO Ltd. Oct. 20, 1961 [Nov. 1, 1960; Nov. 11, 1960], No. 37803/61. Addition to 912,464. Heading D1L. A coating process of the type comprising contacting the surface to be coated with a bed of particulate coating material in a state of even aeration in which the coating material has such free flowing properties as to allow substantially uniform contacting of the surface to be coated, intermediate between that of the material in a fluidised bed condition and the condition of loosely settled material, during at least a substantial part of the coating period while maintaining conditions suitable to cause the adherence of the particles to the surface to be coated, either by rendering the surface itself adhesive or by heating it to a temperature at which the particles become at least plastiform enough to adhere to the surface, further comprises the feature that the surface to be coated is that of a continuous strip of sheet material or wire or other continuous material and that the surface is continuously passed through a zone of contact with the bed of particulate coating material in the above-defined state of aeration. In the embodiment of Fig. 1 an aerating vessel 1 is kept supplied with a thermoplastic powder 2 from a hopper 3. The bottom of the aerating space of vessel 1 is partly formed by a gas-pervious bed 4 underneath which a gas chamber 5 is provided which is supplied with compressed air or other suitable gas through inlet 6. The aerating space drops steeply in the central portion 7 where the bottom of the vessel is formed by guide and sealing rollers 8 and resilient blades 9, 10 represents a continuous strip of material to be coated which travels in the direction of the arrow. The material is preheated in zone 10 and the rollers 8 may be water cooled. For bringing the strip to the exact required temperature induction coils 12 are provided in portion 7 of the aerating vessel. Powder layers 13 are picked up by the strip but are only partly fused initially. The layers 13 are subjected to an embossing effect by rollers 14 and finally fused by induction coils 15. Cooling fans 16 and a quenching zone 16a are provided for cooling purposes. Alternatively the material may be guide through a quenching bath after the embossing rollers 14. The apparatus may be modified to coat one side only of the strip material the latter then forming one side of the aerating vessel. In a further modification the apparatus is adapted to apply multilayer coatings, one after the other, on one or both sides of the strip or multilayers on one side together with a single layer on the other side. If a non-fusible powder is to be used the strip before being brought into contact with the powder is coated with an adhesive by means of a roller applicator. In another embodiment the strip material is passed downwards into a vessel containing the coating material, then around a guide roller and upwards out of the vessel. The apparatus may also be adapted to coat wire, cables &c. Fig. 3 shows apparatus for coating two strips of material on one side only, simultaneously by passing the strips back to back through the aerating vessel containing the coating material. The strips 10a and 10b are supplied from rolls 43a, 43b and an endless belt 44, coated on both sides with a pressure sensitive silicone adhesive, is sandwiched between them. The three are passed between pressure rollers 46 so as to bring about adhesion and sealing of the edges at least, and then into the coating apparatus 42, 45 is a means to renew the adhesive on the belt 44 if necessary. After passing through the coating apparatus the two strips are separated and coiled up at 47a and 47b respectively. Specification 1,008,204 is referred to.