In the coating of plastic onto aluminum foil or different metallic foil it has been found that the coating can happen via a normal extrusion course of which implies the extrusion of a melted plastic mass under high pressure through a narrow, slotlike opening to type a skinny movie which is precipitated onto the steel foil layer, whereupon the metallic foil coated with the plastic materials is introduced between compressive rollers, which at the similar time have a cooling effect. automatic biscuit production line is kind of attainable in itself to provide by this methodology a relatively good adhesion between the coated plastic layer and the metallic foil layer, which, furthermore, may be combined in advance with the mentioned base paper layer, however in such a case the extrusion of plastic material needs to be carried out at a very excessive temperature, that's to say at a temperature which on the extrusion of polyethylene exceeds 300° C. At this comparatively high temperature the plastic material is uncovered to a surface oxidation which unfortunately has the result that the plastic layer can no longer be heat-sealed as easily as if it had not been oxidized. As it's imperative that the inside layer of the packing laminate should be heat-sealable, since in any other case tight packages cannot be obtained, it is necessary in the coating of the plastic materials onto the metal foil layer to use an extrusion temperature which is so low that the plastic materials just isn't oxidized. Approximately and within the alternative of the extrusion temperature a quantity of outside factors have to be taken under consideration, corresponding to e.g., the plastic quality, the room temperature, the rate of extrusion and so forth.
The packing laminate of the sort concerned right here moreover regularly includes a base layer of some kind, particularly paper of carton, and in addition linings of thermoplastic material, which linings on the one hand are supposed to protect the finished packages from moisture and wetness, then again have the thing of creating the packing laminate heat-sealable and eventually have the item of becoming a member of together the fabric layer launched into the laminate. The aspect of the packing laminate which will be turned toward the inside of the completed package deal is generally covered with a layer of thermoplastic material, e.g., polyethylene, and the material layer following this is normally constituted of a metallic foil layer which then in its turn is mounted to a supporting paper layer with the help of an intermediate thermoplastic coat of e.g., polyethylene. Finally, the surface of the packing laminate, that is to say the facet of the packing laminate which will type the outside of the package deal, shall be supplied 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 could additionally be appropriate in certain cases to heat the metal foil layer to a temperature which appreciably exceeds 100° C., e.g., 150° - 200° C., however to forestall in this case the plastic layer from melting down it could be applicable to apply a cooling fuel, e.g., a chilly air in opposition to the outside of the plastic layer 3. Naturally it is potential within the framework of the idea of the invention to arrange the coils, via which the electromagnetic subject is generated, in some other method than that shown right here, but sensible experiments have instructed that the embodiment described here is very appropriate, a minimal of within the remedy of comparatively flexible materials webs. It may after all be appropriate typically to chill the coil windings, that's to say the bars 6 which may readily be accomplished by offering the bars 6 with bores by way of which a cooling liquid can be made to flow into.
Finally a second pair of compression rollers is designated 10 and a magazine roller for the finished packing materials is designated eleven. The present invention considerations a way for the manufacture of laminated packing materials containing no less than one layer of a metal foil, e.g., aluminum foil, and a layer of plastic material applied to the stated metal foil. The invention additionally considerations an apparatus for the realization of the method for the manufacture of laminated packing materials. Modern packages, that are manufactured from an online of packing laminate or from sheet of laminated materials, frequently comprise a layer of a metallic foil, in particular aluminum foil, which lends the packing laminate superb tightness characteristics towards gases and furthermore gives very efficient gentle protection.
As mentioned above, a worse adhesion is obtained between plastic layer and metallic foil layer if the extrusion temperature is low, which implies that the plastic layer within the finished bundle could delaminate and thus in precept type a plastic bag contained in the bundle which is free from the steel foil layer. This after all is not fascinating, but it should be the thing to acquire a non-oxidized internal plastic layer as properly as good adhesion between plastic layer and metal 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 had to be adjusted and maintained very accurately, which may trigger nice difficulties. The invention is characterized further in that the gadget for the execution of the stated second operational stage consists of one of several coils ideally arranged in a single aircraft, which are connectable to a supply of present which can ship an a.c. In the FIGURE numeral 1 refers to a laminate net the upward turned layer of which consists of a steel foil layer or a metallic foil web. Furthermore a pair of compression rollers cooperating with each other is marked 4 and a pair of information rollers 5. A excessive frequency present supply is designated 9 and the feed traces from the supply of present 9 to the bars 6 are marked eight.