Tube and method of making the same

BACKGROUND OF THE INVENTION The present invention relates to a tube with a tube and a head which is manufactured independently of the tube and welded therewith by means of a thermoplastic plastic disposed on both parts, and to a method for its production.

Tubes whose tubes and heads are manufactured separately and welded together as prefabricated parts are known. The manufacturing methods required for the manufacture of these parts are contemplated for the production of plastic tubes themselves - or plastic tubes - with a metal sealing layer. Compared to the method by which a tube is manufactured by placing the head on a tube, for example by spraying in a mold, said methods have the advantage that they can be produced on less expensive machines. In this way, downtime is avoided which causes the accumulated plasticized material to solidify.

However, both methods have the disadvantage that they can only be used in such tubes in which the immediately adjacent portions of the tube and - the tube - are made of thermoplastically bondable plastics. Therefore, these processes cannot be used, for example, in the manufacture of tubes in which the upper edge of the tube is surrounded by a shoulder part of the plastic head, the inner side of the tube at least at this upper edge being not made of thermoplastically-bondable plastic. This is, for example, in those cases where the tubes are provided with barrier layers to prevent diffusion.

There is also a method in which the connection between a tube made of laminated material with a metal layer on one side and a tube head on the other side is made by induction welding. By induction welding - in the - metal layer - of the tubular tube, heat is generated, which is distributed for the intended purpose up to the shoulder part by means of a tube passing - into this shoulder part - overlapping the head part there. It is not possible to prevent the heat generated in this layer in the shoulder part from passing over to other parts in which it is unnecessary, or where it can even cause harmful effects, and to cause, for example, deformation and discoloration. or even blisters in the packaging film. Even though measures are known in connection with this known method, such as cooling the tubular body portions immediately adjacent to the locations of the weld during welding, it is still necessary to supply relatively more heat than the you need - for your own welding.

In many cases, the loss of heat, i.e. the heat dissipated by the metal layer, cannot be generated without prolonging the production times of the individual pieces. In the thin-walled metal insert, no amount of heat can be produced in the short term without the laminated film. damaged or even destroyed.

According to another known solution, the end of the tube is divided into individual parts which are then folded over the shoulder part, or the end of the tube is contracted by folds so as to cover the shoulder part of the head. Both of these known solutions are difficult to use rationally in production. In addition, there is a risk that the currents formed in the individual portions form a short connection with each other so that the metal foil can burn, and the folding of the arm portion by folds tends to break the metal foil under the pressure required to connect the head and arm portions. effective diffusion prevention is not guaranteed.

According to other known solutions, diffusion is to be prevented by a plug insert injected or inserted into the head part. However, the effectiveness of this measure depends essentially on. how small is the distance between the closing layers of the arm portion or the tubular body from each other.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide tubes which, with as low a production cost as possible, meet high leak tightness requirements, particularly with regard to diffusion. Furthermore, this tube is also to be suitable for chemically active substances which attack, for example, metals such as aluminum.

According to the invention, this object is achieved by a ring-shaped connecting body formed at least partly of plastic and overlapping the adjacent peripheral edges of the tube and the tube head from the outside or inside.

By using an annular connecting body it is possible to extend the field of application of these tubes to completely different materials and arrangements. The use can be further expanded if the connecting body is made of several layers.

According to a further feature of the invention, the packaging tube is arranged such that the connecting body is simultaneously formed as a sealing layer. For example, in the case of a tube having a metal closure layer, the connecting body can also be provided with a metal layer which extends, for example, up to the tube outlet. Such a body with a sealing layer forms, for example, diffusion closures.

A further embodiment of the invention relates to a particularly simple arrangement for reliably sealing a tube by means of a tube lid.

The invention relates to a process for the manufacture of a tube by the induction heating of a connection body comprising a thermoforming layer.

A further advantage of this solution is that the thermoforming layer is simultaneously formed as a diffusion-proof layer and can simply extend to the neck without interrupting the arm portion of the tube.

DETAILED DESCRIPTION OF THE INVENTION The invention is illustrated in more detail in the accompanying drawings, in which: Figure 1 is a first exemplary embodiment in axial section; Fig. 2 is a second exemplary embodiment of the invention provided with a metal sealing layer; Fig. 3 is a third exemplary embodiment in axial section; Fig. 4 is a fourth exemplary embodiment - axial section; and Fig. 5 is a sectional view; - parts - of the packaging tube according to FIG. 4 prior to -welding it, together with the weld-splicing device.

In Fig. 1, the tube has a tube 2 shown only at its end on the head side; the tube further has a head 4. The tube 2 consists of three layers, i.e. the outer layer 6 of polyethylene, the - closing layer 8 of polyester and the - inner layer 10 - also of polyethylene. Binder layers are not shown in the drawing, such as copolymers, which may be needed, for example, to achieve permanent bonding of the closure layer materials, in the form of a laminate, and to form outer layers especially of thermoplastic.

The head 4 has a spout 12 provided with a threaded and an arm portion 14 adjoining the spout 12, the head 4 being made in a known manner by spraying from polyethylene.

The tube 2 is connected to the head 4 by a connecting body 16 having a plate-like shape. The connecting body 16 overlaps both the upper end of the tube 2 and the arm portion 14 outside and always in the annular zones. In this connection, the connecting body 16 has two main layers, namely the sealing layer 18 of polyester and the covering layer 20 of polyethylene. In order to guarantee or improve the connection to the cover layer -20 and in particular to the overlapping arm portion 14 and overlapping outer portion 6, the polyester portion of the barrier layer 18 is provided with a copolymer layer on both sides.

The connection of the connecting body 16 to the tube 2 and the head 4 is preferably carried out in the same working step. The contact surfaces of these parts, for example, are melted by radiant heat and compressed together, for example in a two-piece mold. The material is extruded from the polyethylene layers 6, 10 by heat and pressure

22.

In the embodiment shown in Fig. 2, the tube-ears of the tube of Fig. 1, in particular by arranging and - the sealing layer material on the connecting body 16. In this case, the connecting body 16 has a sealing layer 30 of aluminum and an inner layer 32, for example of polyethylene. The polyethylene layer can be laminated to an aluminum layer in a known manner by means of a copolymer layer.

The tube 2 has, instead of a polyester sealing layer, a sealing layer 34 of metal, in particular of aluminum, arranged between the polyethylene layers 6, 10. The upper edge of the tube 2 is on its inner side covered by a collar portion 36, which is double-fitted with respect to the arm portion 38, thereby preventing the fill material from coming into contact with the aluminum of the barrier layer 34.

The method of manufacturing the tube of FIG. 2 is particularly simple, since the thermoplastic plastic can be heated by contact heating immediately - the aluminum sealing layer 30, the head 4, the tube 2 and the connecting body 16 can be in sequence

5 7 2 9 are applied to a mandrel, with which the matrix corresponding to the final part of the connecting body is heated.

Fig. 3 shows an exemplary embodiment with a tube 2j whose construction corresponds to the example of Figs. 2 and which is overlapped on its inner side by a connecting body 40. The body 40 consists of an aluminum barrier layer 42, as well as an outer layer 44a and an inner layer 46 of polyethylene and has a shaped cylindrical neck portion 48. a tubular head 50 of polyethylene. The neck portion 48 engages in the annular groove 52 in the tubular head 50 formed as an outlet. The tubular head 50 is an annular groove 52 inwardly integrated into the sleeve 54 and outwardly into the collar 56. For attachment, at least the inner layer 46 of the connector body 40 is welded to the adjacent surface of the sleeve 54. provided with a thread for incorporating a closure cap (not shown).

Fig. 4 shows a further embodiment with a tube 2 connecting body 60; and the head portion 62. The tube 2 is again made of a three-layer composite material, the inner layer 10 and the outer layer 6 of which are mainly made of polyethylene, the middle layer 34 and the made-up layer. of metal, in particular of aluminum. The connecting body 60 consists of a three-layer laminate consisting of an outer layer 64 and an inner layer 66 as well as a sealing layer 68. The sealing layer 68 is mainly made of an aluminum alloy. The layers 64 and 66 are heat-sealable layers and are preferably formed of a polyethylene or a copolymer that adheres well to an aluminum layer. The head portion 62 is formed as a shaped body; a plastic, such as polyethylene, formed in a known manner by spraying.

The threaded portion of the head 62 has an annular groove 70, thereby forming a sleeve 72 that prevents rapid backflow of filled material immediately after removal. This largely prevents the introduction of air harmful to the material to be filled. In this exemplary embodiment, the annular groove 70 may be lined with a ring, not shown in the drawing, and which is made of a material with diffusion prevention properties.

The head portion 62 further has an arm portion 74 which forms a stop and a first sealing surface for a screw cap that is not shown, not shown. An additional sealing surface which interacts with the closure cap can only be effective if it is resilient. Accordingly, the closure cap can be sized such that by its inner base surface it presses against the annular sealing projection 76 disposed on the head 62. Another possibility for a different sealing surface is provided by the bevel 78 above the external thread of the head 62, which bevel 78 must be adapted to the closure cap. The sealing lip 76 or bevel 78 'also acts as a resilient seal in conjunction with the closure cap of plastic. which may, within certain limits, compensate for manufacturing tolerances. ,

The exemplary embodiments of the connecting bodies 16, 40, 60 & apos; have a double function, i. extend the sealing layer, tube 2, to the arm portion of the tube, 2. The embodiment shown in FIG. 3 provides a further extension. sealing layer into the outlet. Therefore, the tube thus arranged is particularly suitable for sensitive materials to be filled.

While, in the example, the embodiment according to FIG. 2, there is a direct connection between the tube 2 and the head 4 as a result of the embodiment and the material, this measure is not necessary in the embodiment according to FIG. The connection body 16, 40, 60 is not influenced by the change in wall thickness but by the choice and arrangement of the layers. /

In principle, of course, it is also possible to integrate the coupling body and to integrate the head in such a way that a separate casting and joining is eliminated. ^; , for, this part. In the example of the embodiment of Fig. 3, it is possible to weld the head 50 with the coupling body 40, for example by frictional heat, before coupling with the tube 2.

The connecting bodies 16 according to the exemplary embodiments of FIGS. 1 and 2 can be prefabricated by pressing, stamping or deep drawing the laminate material. In the connection body 40 of FIG. 3, winding is also possible, wherein the coil is also embossed from the respective laminate, and the edges are overlapped in the seam into the ring.

Of course, tubular bodies can also be formed by winding.

In the embodiment of FIG. 3, the metal barrier layer 42 is insulated from the filled material within the tube of plastic layers 46 by overflowing its material during welding.

FIG. 5 shows the production of the packaging tube according to FIG. 4 by the method of the invention. This method relates exclusively to exemplary embodiments, in which the connecting body 60 has an induction-controlled temperature-controlled layer, for example a metal layer.

As can be seen from FIG. 5, the head 80 is arranged on the mandrel 82. The connecting body 60 is then fitted to the head 80 in a suitable manner and the tube 2 is brought to a suitable position for welding and shaped, narrowing ^; 84. 'Then' with the pressing tool · 86 s, the induction coil 88 creates the heat and pressure needed for the coupling.

It goes without saying that the individual steps of the method need not necessarily follow the sequence described above. In particular, it is also possible, for example, to first establish a connection between the coupling body 60, the head 80 or between the tube 2 and the coupling body 60 separately. '

The arrangement and the embodiment make it possible to generate the required heat of welding exclusively in the connector body 60. This can, in the example embodiment, in which the connector body has a substantially thicker metal layer than the tube 2, such that is set to a thicker metal layer contained in the connector body 60 so that the metal layer in the tube is virtually unheated.

Another possibility is to concentrate the magnetic fields at the connection body by a suitable design of the induction coil. Also, the use of magnetically conductive materials operating as losslessly as possible, such as ferrites or cores of powdered metal, can significantly increase the magnetic field concentration. Instead of the embodiment of FIG. 5, it is also possible to arrange the induction source in the mandrel 82 and optionally shield the field in the zone of the tube 2. Since this arrangement allows the tool 86 to be made of metal, the cooling time after welding can be considerably shortened.

As described above, the cutting edges 90, 92, 94 shown in FIG. 4 are covered by overflowing plastic so that there is no direct contact between the material to be filled and the metal and no cutting edges are visible on the outside of the tube.

A particular advantage of the embodiment according to FIG. 4 is that the spacing of the sealing layers 34, 68 of the tube 2 or the connecting body 60 forming the arm portion is as small as possible and the overlap of the sealing layers 34, 68 can be kept as large as possible. Thereby, the diffusion path is large, so that a good anti-diffusion effect is obtained.

SUBJECT