Notes

The packing laminate of the sort concerned right here furthermore frequently comprises a base layer of some sort, in particular paper of carton, and also linings of thermoplastic materials, which linings on the one hand are meant to guard the finished packages from moisture and wetness, then again have the object of making the packing laminate heat-sealable and eventually have the object of becoming a member of collectively the fabric layer introduced into the laminate. The side of the packing laminate which shall be turned toward the within of the completed package is usually lined with a layer of thermoplastic material, e.g., polyethylene, and the material layer following that is often 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 outside of the packing laminate, that's to say the aspect of the packing laminate which will kind the outside of the package deal, might be provided with a thermoplastic coat of e.g., polyethylene, which has as its object the safety of the bottom layer of paper and the prevention of the absorption of moisture by the said layer. It may be acceptable in certain instances to heat the steel 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 might be acceptable to use a cooling fuel, e.g., a cold air in opposition to the surface of the plastic layer 3. Naturally it's attainable inside the framework of the idea of the invention to rearrange the coils, by the use of which the electromagnetic area is generated, in some other method than that shown right here, however practical experiments have suggested that the embodiment described right here is very suitable, no much less than within the therapy of comparatively versatile materials webs. It might in fact be applicable generally to cool the coil windings, that's to say the bars 6 which might readily be done by providing the bars 6 with bores via which a cooling liquid may be made to circulate.
As talked about above, a worse adhesion is obtained between plastic layer and steel foil layer if the extrusion temperature is low, which implies that the plastic layer in the finished bundle could delaminate and thus in precept form a plastic bag contained in the bundle which is free from the metal foil layer. This of course isn't fascinating, nevertheless it should be the object to obtain a non-oxidized inner plastic layer as well as good adhesion between plastic layer and steel foil, and in order to obtain this it was essential to just accept a compromise between sealability and lamination energy and accordingly the lamination temperature had to be adjusted and maintained very precisely, which may cause nice difficulties. The invention is characterised additional in that the device for the execution of the said second operational stage consists of one of a number of coils ideally organized in a single aircraft, that are connectable to a source of current which can deliver 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 metallic foil net. Furthermore a pair of compression rollers cooperating with one another is marked four and a pair of guide rollers 5. A high frequency current source is designated 9 and the feed traces from the source of present 9 to the bars 6 are marked eight.
In the coating of plastic onto aluminum foil or other metal foil it has been found that the coating can take place by means of a normal extrusion process which means the extrusion of a melted plastic mass underneath high strain via a narrow, slotlike opening to form a thin film which is precipitated onto the metal foil layer, whereupon the steel foil coated with the plastic materials is launched between compressive rollers, which at the identical time have a cooling effect. Snack Food Extruder is type of possible in itself to supply by this technique a comparatively good adhesion between the coated plastic layer and the metal foil layer, which, furthermore, could be mixed upfront with the stated base paper layer, however in such a case the extrusion of plastic materials has to 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 comparatively high temperature the plastic materials is uncovered to a surface oxidation which unfortunately has the result that the plastic layer can not be heat-sealed as easily as if it had not been oxidized. As it's imperative that the within layer of the packing laminate should be heat-sealable, since otherwise tight packages can't be obtained, it is necessary in the coating of the plastic materials onto the metallic foil layer to make use of an extrusion temperature which is so low that the plastic material isn't oxidized. Approximately and within the selection of the extrusion temperature a number of outside factors need to be taken into consideration, similar to e.g., the plastic quality, the room temperature, the speed of extrusion and so on.
Finally a second pair of compression rollers is designated 10 and a magazine curler for the finished packing material is designated eleven. snack machine for the manufacture of laminated packing materials containing a minimal of one layer of a steel foil, e.g., aluminum foil, and a layer of plastic materials applied to the said steel foil. biscuit production line concerns an equipment for the realization of the tactic for the manufacture of laminated packing material. Modern packages, which are manufactured from a web of packing laminate or from sheet of laminated material, frequently comprise a layer of a steel foil, specifically aluminum foil, which lends the packing laminate very good tightness traits in opposition to gases and moreover provides very efficient light safety.
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