Notes

The packing laminate of the sort involved here moreover regularly comprises a base layer of some kind, specifically paper of carton, and in addition linings of thermoplastic material, which linings on the one hand are intended to guard the completed packages from moisture and wetness, however have the object of creating the packing laminate heat-sealable and at last have the item of becoming a member of together the material layer introduced into the laminate. The aspect of the packing laminate which shall be turned towards the inside of the completed package deal is usually coated with a layer of thermoplastic materials, e.g., polyethylene, and the fabric layer following that is normally constituted of a steel foil layer which then in its turn is fastened to a supporting paper layer with the assistance of an intermediate thermoplastic coat of e.g., polyethylene. Finally, the outside of the packing laminate, that's to say the facet of the packing laminate which can kind the outside of the bundle, will be provided with a thermoplastic coat of e.g., polyethylene, which has as its object the safety of the base layer of paper and the prevention of the absorption of moisture by the mentioned layer. It may be acceptable in sure instances to heat the metal foil layer to a temperature which appreciably exceeds 100° C., e.g., 150° - 200° C., however to stop on this case the plastic layer from melting down it may be appropriate to use a cooling gas, e.g., a chilly air against the surface of the plastic layer three. Naturally it's potential inside the framework of the concept of the invention to arrange the coils, via which the electromagnetic subject is generated, in another manner than that shown here, but sensible experiments have advised that the embodiment described here is particularly suitable, a minimal of in the therapy of comparatively flexible materials webs. It may in fact be applicable typically to chill the coil windings, that's to say the bars 6 which may readily be done by providing the bars 6 with bores by way of which a cooling liquid may be made to flow into.
Finally a second pair of compression rollers is designated 10 and a journal roller for the finished packing materials is designated 11. food extruder 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 utilized to the said metal foil. The invention also issues an apparatus for the conclusion of the strategy for the manufacture of laminated packing materials. Modern packages, that are manufactured from a web of packing laminate or from sheet of laminated materials, regularly comprise a layer of a metallic foil, in particular aluminum foil, which lends the packing laminate excellent tightness traits towards gases and moreover offers very effective gentle protection.
As talked about above, a worse adhesion is obtained between plastic layer and metallic foil layer if the extrusion temperature is low, which means that the plastic layer within the finished package could delaminate and thus in precept form a plastic bag inside the bundle which is free from the metal foil layer. This after all is not fascinating, but it should be the item to obtain a non-oxidized internal plastic layer as nicely as good adhesion between plastic layer and metal foil, and in order to obtain this it was needed to simply accept a compromise between sealability and lamination strength and accordingly the lamination temperature had to be adjusted and maintained very precisely, which can trigger nice difficulties. The invention is characterized additional in that the device for the execution of the mentioned second operational stage consists of certainly one of several coils preferably organized in a single airplane, which are connectable to a source of current which might ship an a.c. In the FIGURE numeral 1 refers to a laminate internet the upward turned layer of which consists of a metal foil layer or a metal foil net. Furthermore a pair of compression rollers cooperating with one another is marked 4 and a pair of guide rollers 5. A high frequency current source is designated 9 and the feed strains from the source of current 9 to the bars 6 are marked eight.
In the coating of plastic onto aluminum foil or other metallic foil it has been discovered that the coating can happen via a traditional extrusion process which implies the extrusion of a melted plastic mass underneath excessive stress by way of a narrow, slotlike opening to form a skinny movie which is precipitated onto the metallic foil layer, whereupon the metallic foil coated with the plastic material is introduced between compressive rollers, which on the similar time have a cooling effect. It is sort of potential in itself to supply by this technique a relatively good adhesion between the coated plastic layer and the metallic foil layer, which, furthermore, can be combined in advance with the said base paper layer, however in such a case the extrusion of plastic materials needs to be carried out at a very excessive temperature, that is to say at a temperature which at the extrusion of polyethylene exceeds 300° C. At this comparatively excessive temperature the plastic materials is uncovered to a floor oxidation which sadly has the outcome that the plastic layer can no longer be heat-sealed as simply as if it had not been oxidized. As it's imperative that the inside layer of the packing laminate must be heat-sealable, since otherwise tight packages cannot be obtained, it is essential in the coating of the plastic materials onto the metal foil layer to use an extrusion temperature which is so low that the plastic material just isn't oxidized. Approximately and in the choice of the extrusion temperature a quantity of outdoors components should be taken into consideration, such as e.g., the plastic high quality, the room temperature, the speed of extrusion and so forth.
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