Notes

In the coating of plastic onto aluminum foil or different steel foil it has been discovered that the coating can happen by means of a normal extrusion process which means the extrusion of a melted plastic mass underneath high stress via a slim, slotlike opening to type a thin 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 identical time have a cooling impact. It is kind of potential in itself to supply by this methodology a comparatively good adhesion between the coated plastic layer and the steel foil layer, which, moreover, may be combined in advance with the mentioned base paper layer, but in such a case the extrusion of plastic materials needs to 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 excessive temperature the plastic material is exposed to a floor oxidation which sadly has the result that the plastic layer can now not be heat-sealed as easily as if it had not been oxidized. As it is crucial that the inside layer of the packing laminate must be heat-sealable, since otherwise 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 isn't oxidized. Approximately and within the selection of the extrusion temperature a quantity of outdoors elements should be taken into account, such as e.g., the plastic high quality, the room temperature, the rate of extrusion etc.
As mentioned above, biscuit making machine is obtained between plastic layer and metallic foil layer if the extrusion temperature is low, which means that the plastic layer in the completed package deal might delaminate and thus in precept form a plastic bag contained in the package which is free from the metallic foil layer. This of course isn't fascinating, but it have to be the thing to acquire a non-oxidized inside plastic layer in addition to good adhesion between plastic layer and steel foil, and so as to obtain this it was essential to merely accept a compromise between sealability and lamination power and accordingly the lamination temperature needed to be adjusted and maintained very precisely, which can cause great difficulties. The invention is characterized additional in that the device for the execution of the mentioned second operational stage consists of considered one of several coils preferably organized in one plane, which are connectable to a supply 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 metal foil layer or a metal foil net. Furthermore a pair of compression rollers cooperating with each other is marked 4 and a pair of guide rollers 5. A excessive frequency present source 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 involved here moreover frequently comprises a base layer of some kind, in particular paper of carton, and likewise linings of thermoplastic material, which linings on the one hand are meant to protect the completed packages from moisture and wetness, on the opposite hand have the thing of making the packing laminate heat-sealable and at last have the item of becoming a member of collectively the material layer launched into the laminate. The facet of the packing laminate which might be turned toward the within of the completed package deal is usually covered with a layer of thermoplastic materials, e.g., polyethylene, and the material layer following that is usually constituted of a metal foil layer which then in its flip is mounted 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's to say the aspect of the packing laminate which is ready to type the skin of the bundle, might 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 acceptable in certain instances to warmth the steel 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 could be applicable to use a cooling gas, e.g., a chilly air against the outside of the plastic layer three. Naturally it is possible inside the framework of the concept of the invention to arrange the coils, by means of which the electromagnetic subject is generated, in another method than that proven right here, however sensible experiments have instructed that the embodiment described here is especially suitable, no much less than within the treatment of relatively flexible materials webs. It may in fact be appropriate sometimes to chill the coil windings, that's to say the bars 6 which can readily be accomplished by offering the bars 6 with bores via which a cooling liquid may be made to circulate.
Finally a second pair of compression rollers is designated 10 and a magazine curler for the completed packing materials is designated 11. The present invention considerations 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 additionally concerns an apparatus for the belief of the method for the manufacture of laminated packing material. Modern packages, which are manufactured from an internet of packing laminate or from sheet of laminated material, incessantly comprise a layer of a metal foil, specifically aluminum foil, which lends the packing laminate very good tightness characteristics against gases and moreover offers very effective mild safety.
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