Notes

Finally a second pair of compression rollers is designated 10 and a journal roller for the finished packing material is designated 11. The current invention issues a method for the manufacture of laminated packing materials containing a minimal of one layer of a metal foil, e.g., aluminum foil, and a layer of plastic material applied to the mentioned steel foil. The invention additionally considerations 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, frequently comprise a layer of a steel foil, specifically aluminum foil, which lends the packing laminate very good tightness characteristics against gases and furthermore offers very effective gentle safety.
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 finished package may delaminate and thus in principle kind a plastic bag contained in the package deal which is free from the metal foil layer. biscuit production machine in fact is not desirable, but it must be the item to obtain 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 necessary 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 cause nice difficulties. The invention is characterised further in that the system for the execution of the said second operational stage consists of considered one of several coils ideally arranged in one plane, that are connectable to a source of current which can deliver an a.c. In snack machine refers to a laminate net the upward turned layer of which consists of a metal foil layer or a steel foil net. Furthermore a pair of compression rollers cooperating with each other is marked four and a pair of information rollers 5. A high frequency current supply is designated 9 and the feed strains from the supply of present 9 to the bars 6 are marked 8.
In the coating of plastic onto aluminum foil or other steel foil it has been found that the coating can happen by the use of a normal extrusion process which implies the extrusion of a melted plastic mass underneath excessive strain through a slim, slotlike opening to type a thin film which is precipitated onto the metal foil layer, whereupon the steel foil coated with the plastic materials is introduced between compressive rollers, which at the same time have a cooling impact. It is sort of potential in itself to produce by this method a relatively good adhesion between the coated plastic layer and the steel foil layer, which, furthermore, can be combined prematurely with the mentioned base paper layer, however in such a case the extrusion of plastic materials needs to be carried out at a very high temperature, that is to say at a temperature which at the extrusion of polyethylene exceeds 300° C. At this relatively excessive temperature the plastic materials is exposed 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 it's crucial that the inside layer of the packing laminate must be heat-sealable, since otherwise tight packages cannot be obtained, it's necessary in the coating of the plastic material onto the metallic foil layer to use an extrusion temperature which is so low that the plastic materials is not oxidized. Approximately and within the choice of the extrusion temperature a selection of outside factors should be taken into consideration, such as e.g., the plastic quality, the room temperature, the speed of extrusion etc.
The packing laminate of the kind involved right here moreover frequently contains a base layer of some kind, in particular paper of carton, and also linings of thermoplastic materials, which linings on the one hand are meant to protect the finished packages from moisture and wetness, however have the thing of making the packing laminate heat-sealable and eventually have the thing of becoming a member of together the material layer introduced into the laminate. The aspect of the packing laminate which shall be turned toward the within of the finished bundle is generally covered with a layer of thermoplastic material, e.g., polyethylene, and the material layer following that is usually constituted of a steel foil layer which then in its flip is fixed 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 side of the packing laminate which is in a position to kind the surface of the package deal, 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 said layer. It could also be acceptable in certain circumstances to warmth the metal foil layer to a temperature which appreciably exceeds 100° C., e.g., 150° - 200° C., but to prevent on this case the plastic layer from melting down it might be acceptable to use a cooling fuel, e.g., a cold air towards the skin of the plastic layer three. Naturally it's possible within the framework of the idea of the invention to rearrange the coils, by means of which the electromagnetic field is generated, in another method than that proven right here, however sensible experiments have suggested that the embodiment described here is particularly appropriate, at least within the treatment of relatively versatile materials webs. It could in fact be applicable generally to cool the coil windings, that is to say the bars 6 which may readily be accomplished by providing the bars 6 with bores by way of which a cooling liquid may be made to flow into.
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