Notes

The packing laminate of the type involved here furthermore regularly includes a base layer of some sort, in particular paper of carton, and also linings of thermoplastic material, which linings on the one hand are intended to protect the finished 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 collectively the material layer introduced into the laminate. The facet of the packing laminate which will be turned towards the inside of the finished package deal is mostly covered with a layer of thermoplastic materials, e.g., polyethylene, and the fabric layer following this is normally constituted of a steel 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 skin of the packing laminate, that is to say the aspect of the packing laminate which is able to form the outside of the bundle, will 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 stated layer. It may be appropriate in sure cases to warmth the metal foil layer to a temperature which appreciably exceeds 100° C., e.g., 150° - 200° C., however to forestall on this case the plastic layer from melting down it might be appropriate to use a cooling gas, e.g., a chilly air against the surface of the plastic layer 3. Naturally it's attainable throughout the framework of the idea of the invention to rearrange the coils, via which the electromagnetic subject is generated, in another manner than that shown right here, however practical experiments have suggested that the embodiment described right here is particularly suitable, no much less than within the treatment of comparatively versatile material webs. It might of course be acceptable sometimes to chill the coil windings, that's to say the bars 6 which might readily be accomplished by providing the bars 6 with bores by way of which a cooling liquid could be made to flow into.
Finally Snack Food Machine of compression rollers is designated 10 and a magazine roller for the completed packing material is designated eleven. The current invention concerns a technique for the manufacture of laminated packing materials containing at least one layer of a metallic foil, e.g., aluminum foil, and a layer of plastic material utilized to the said metallic foil. The invention also issues an equipment for the realization of the tactic 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, particularly aluminum foil, which lends the packing laminate superb tightness traits towards gases and moreover offers very effective mild safety.
In the coating of plastic onto aluminum foil or different metal foil it has been found that the coating can take place via a standard extrusion course of which implies the extrusion of a melted plastic mass underneath high strain by way of a narrow, slotlike opening to form a skinny film which is precipitated onto the metal foil layer, whereupon the metallic foil coated with the plastic material is launched between compressive rollers, which on the same time have a cooling impact. It is type of attainable in itself to supply by this methodology a comparatively good adhesion between the coated plastic layer and the metallic foil layer, which, furthermore, may be mixed upfront with the said base paper layer, however in such a case the extrusion of plastic material must be carried out at a really 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 materials is uncovered to a floor oxidation which sadly has the result that the plastic layer can now not be heat-sealed as simply as if it had not been oxidized. As Snack Food Machine is crucial that the inside layer of the packing laminate must be heat-sealable, since otherwise tight packages can't be obtained, it is needed within 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 just isn't oxidized. Approximately and in the selection of the extrusion temperature a quantity of exterior factors have to be taken under consideration, such as 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 steel foil layer if the extrusion temperature is low, which suggests that the plastic layer in the completed package deal might delaminate and thus in principle form a plastic bag inside the package deal which is free from the metal foil layer. This in fact isn't fascinating, but it should be the item to acquire a non-oxidized inside plastic layer in addition to good adhesion between plastic layer and metal foil, and to find a way to achieve 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 precisely, which may trigger great difficulties. The invention is characterised further in that the gadget for the execution of the stated second operational stage consists of certainly one of several coils preferably arranged in one airplane, that are connectable to a source of present which may deliver 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 steel foil internet. Furthermore a pair of compression rollers cooperating with one another is marked four and a pair of guide rollers 5. A excessive frequency current supply is designated 9 and the feed lines from the source of present 9 to the bars 6 are marked 8.
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