Notes

Finally a second pair of compression rollers is designated 10 and a journal roller for the finished packing materials is designated eleven. The current invention concerns a method for the manufacture of laminated packing material containing at least one layer of a metal foil, e.g., aluminum foil, and a layer of plastic materials applied to the stated metallic foil. The invention also issues an apparatus for the belief of the method for the manufacture of laminated packing materials. Modern packages, which are manufactured from a web of packing laminate or from sheet of laminated material, incessantly comprise a layer of a metallic foil, specifically aluminum foil, which lends the packing laminate very good tightness traits towards gases and furthermore gives very efficient light safety.
In the coating of plastic onto aluminum foil or different metal foil it has been discovered that the coating can happen by the use of a standard extrusion course of which suggests the extrusion of a melted plastic mass under excessive strain through a slim, slotlike opening to kind a thin film which is precipitated onto the metallic foil layer, whereupon the metal foil coated with the plastic material is launched between compressive rollers, which at the similar time have a cooling effect. food extruder is kind of attainable in itself to supply by this method a comparatively good adhesion between the coated plastic layer and the steel foil layer, which, moreover, may be mixed prematurely with the stated base paper layer, but in such a case the extrusion of plastic material must be carried out at a very excessive temperature, that's to say at a temperature which at the extrusion of polyethylene exceeds 300° C. At this relatively high temperature the plastic material is uncovered to a surface oxidation which sadly has the outcome that the plastic layer can not be heat-sealed as simply as if it had not been oxidized. As it's crucial that the inside layer of the packing laminate must be heat-sealable, since otherwise tight packages can't be obtained, it's needed in the coating of the plastic material onto the steel foil layer to make use of an extrusion temperature which is so low that the plastic material isn't oxidized. Approximately and in the selection of the extrusion temperature a number of outdoors components have to be taken into account, corresponding to e.g., the plastic quality, the room temperature, the speed of extrusion and so forth.
As mentioned above, a worse adhesion is obtained between plastic layer and metallic foil layer if the extrusion temperature is low, which suggests that the plastic layer within the completed bundle could delaminate and thus in principle kind a plastic bag inside the bundle which is free from the metal foil layer. This after all is not desirable, however it have to be the object to obtain a non-oxidized inner plastic layer as nicely as good adhesion between plastic layer and steel foil, and so as to obtain this it was essential to simply accept a compromise between sealability and lamination strength and accordingly the lamination temperature needed to be adjusted and maintained very accurately, which may cause great difficulties. The invention is characterised further in that the device for the execution of the said second operational stage consists of considered one of several coils preferably arranged in one airplane, that are connectable to a supply of present which might ship an a.c. In the FIGURE numeral 1 refers to a laminate web the upward turned layer of which consists of a metallic foil layer or a metal foil web. Furthermore a pair of compression rollers cooperating with one another is marked 4 and a pair of information rollers 5. A high frequency current supply is designated 9 and the feed traces from the source of current 9 to the bars 6 are marked 8.
The packing laminate of the type concerned right here furthermore frequently comprises a base layer of some sort, particularly paper of carton, and likewise linings of thermoplastic materials, which linings on the one hand are meant to protect the completed packages from moisture and wetness, however have the item of making the packing laminate heat-sealable and at last have the object of joining collectively the material layer launched into the laminate. The facet of the packing laminate which will be turned towards the within of the completed package is usually lined with a layer of thermoplastic material, e.g., polyethylene, and the material layer following this is normally constituted of a metal foil layer which then in its turn is fixed to a supporting paper layer with the assistance of an intermediate thermoplastic coat of e.g., polyethylene. Finally, the skin of the packing laminate, that is to say the aspect of the packing laminate which can type the surface of the package deal, will be provided with a thermoplastic coat of e.g., polyethylene, which has as its object the protection of the bottom layer of paper and the prevention of the absorption of moisture by the mentioned layer. It may be applicable in certain instances to heat the metallic foil layer to a temperature which appreciably exceeds 100° C., e.g., 150° - 200° C., however to prevent on this case the plastic layer from melting down it may be acceptable to apply a cooling gasoline, e.g., a chilly air in opposition to the outside of the plastic layer 3. Naturally biscuit production machine throughout the framework of the idea of the invention to rearrange the coils, via which the electromagnetic subject is generated, in some other method than that proven here, however sensible experiments have advised that the embodiment described here is particularly appropriate, at least within the therapy of comparatively flexible material webs. It could of course be acceptable sometimes to chill the coil windings, that is to say the bars 6 which might readily be done by providing the bars 6 with bores through which a cooling liquid can be made to flow into.
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