FR2598969A1 - Laminate material for packaging, in particular for the manufacture of bottle caps and process for its manufacture - Google Patents

Abstract

The invention relates to a laminate material for packaging, in particular for the manufacture of bottle caps, the core layer of which is formed from soft metal or soft metal alloy and carries, on at least one side, a layer of harder metal or harder metal alloy. This material comprises a printed strip of synthetic material having a core layer 11 of from approximately 20 to approximately 100 mu m thickness formed from the soft metal or soft metal alloy and an impression-carrying layer 12 applied to one of the sides of this core layer 11 and which is formed from a sheet of the harder metal or harder metal alloy, of thickness less than that of the core layer 11 and which has, at least on the side opposite this core layer, a smooth surface on which the relevant impression 14 is applied.

Description

Laminated material for packaging, in particular for the manufacture of bottle caps and method for its manufacture.

The invention relates to a laminated material for packaging, in particular for the manufacture of bottle caps, the core layer of which is formed from soft metal or from a soft metallic alloy and which has a layer of harder metal on at least one side. of harder metal alloy. Furthermore, the invention relates to a method for the manufacture of such a laminated material.
For laminated materials intended for packaging and for bottle caps, a flexible flexible material is often desired capable of marrying the objects to be packaged or the neck of the bottle. It is particularly desirable that it does not form folds or sharp edges and that a soft and flexible feel is obtained. Such properties exist in the case of a tin foil and tin capsules. and they are also obtained approximately with lead sheets and lead capsules. Aluminum foil often used in place of tin often tends to form sharp folds and edges and is significantly harder to the touch than the corresponding tin or lead products.

 DE-OS 30 22 205 also discloses a laminated material in which a core layer of lead or lead alloy is covered on one side with a layer of aluminum. This layer of aluminum is provided to prevent inside a bottle cap made from laminated material, the formation of lead corrosion products and to exclude only lead and lead corrosion products cannot reach the neck of the bottle and the basket stopper which closes it. However, it appeared that this protective measure can be applied, with a protective coating against corrosion and wear formed of currently available synthetic material, in particular of sliding varnish, just as well, if not better, than with a layer of aluminum. On the other hand, it appeared that with the possibilities known by DE-OS 30 22 205, one cannot take full account of the external surface structure of packaging elements, for example bottle caps, even when the lead sheet core layer is lined with aluminum foil on both sides.

 Relative to this, the problem of the invention is to create an improved laminated material with a core layer of soft metal or soft metal alloy and at least one layer of harder metal, for example aluminum, copper, tin etc. for the production of packaging elements such as bottle caps. In particular, the appearance of packaging units must be improved considerably in terms of its appearance, by further reducing the expense of printing ink. Similarly, an improved coating to protect against corrosion and wear on the laminate material must also be provided. With all this, the typical flexible and soft character of a sheet of soft metal or soft metal alloy, for example a sheet of tin, must be maintained as much as possible or be achieved.

 This problem is solved according to the invention by the fact that a strip of printed synthetic material is created having a core layer of approximately 20 to approximately 100 thick formed of the soft metal or of the soft metallic alloy and a print carrier layer applied on one side of this core layer and which is formed of a sheet of harder metal or of the harder metal alloy, thinner than the core layer and which has at least on the side opposite the latter a smooth surface on which the impression in question is applied.

 The print carrier layer may preferably be formed from an aluminum foil or aluminum alloy about 7 to about 40 µm thick. However, copper sheets or other metallic sheets with a smooth surface are also contemplated. Thanks to the invention, on the one hand, the fundamental character of the laminated material is determined by the core layer of soft metal or of a soft metallic alloy such as tin, a tin alloy, lead or a lead alloy, while on the other hand the smooth surface of the metal sheet used as a print carrier layer allows an improved appearance of the print, in particular an improved colored appearance. Printing can be carried out with considerably less expense and less consumption of printing ink, and therefore significantly more economically.

 When using such harder metal sheets which have a shiny side and a natural side, it is possible, as desired, to use the glossy side, the matte side as the side to be printed on. It is particularly recommended to connect the metallic sheet forming the printing carrier to the core layer by means of a layer of adhesive, therefore, practically to laminate on the core layer.

 On the side opposite the print carrier layer, the core layer may preferably be inked with a protective layer against corrosion and wear. This layer can be made in the most diverse way.

In particular, it is recommended that the protective coating against corrosion and wear presses a load-bearing layer in the form of a metal sheet which carries, on the side opposite to the core layer, a functional layer with a layer of material. synthetic. However, the protective coating against corrosion and wear can also fold a functional layer applied directly to the surface of the core layer and which has a matrix of synthetic material. The gangue of synthetic material of the functional layer can etL-e formed of sliding varnish and one can use pure sliding varnish.However, it is also possible to still sssser in this gangue of synthetic material formed of sliding varnish of particles increasing the wear resistance of the functional layer, which can at the same time be particles of pigment for metallic coloring, for example copper color or tin color.

 The manufacture of such a laminated material can be carried out safely and easily by a method according to the invention. According to this, it is necessary to coat a prefabricated sheet of soft metal or of a soft metal alloy such as lead, a lead alloy, tin or a tin alloy, having a thickness of about 20 to about 100 of a harder metal sheet with a smooth surface with a thickness of about 7 to about 50 μm and providing this metal sheet, on its exposed side, by a process of flexography or intaglio printing, with the printing desired.

This process can be implemented in a simple and non-polluting manner and without the formation of significant quantities of waste.

 For this purpose, there are two different possibilities, namely a) print the metal sheet beforehand and then apply, preferably laminate, the print medium provided with a print and possibly with a covering layer resistant to abrasion, on the prefab sheet of soft metal or soft metal alloy, or b) forming a strip of laminated metal material with a layer of soft metal or soft metal alloy and a harder metal layer as a support for the print to apply and then print this strip of laminate material.

 When a metallic foil which has a shiny surface and a matt surface is used as the print carrier layer, it is possible to choose, to print according to the desired appearance of the print, either the shiny surface or the surface mat and in each case bond the other surface to the sheet of soft metal or soft metal alloy. The invention also offers - in particular in the first operating mode indicated above - the possibility of subjecting to an additional pretreatment the sheet of harder metal to be used for the formation of the print carrier layer, in order to form for example in the metallic sheet a desired surface structure, for example a chaffed surface, a structure of textile material, etc. This treatment for the constitution of particular desired surface structures will generally be carried out before the printing of the metallic sheet. After printing, the metal sheet forming the print carrier layer, or the strip of printed laminate material, can be provided with a transparent abrasion-resistant covering layer, covering the print, for example with a transparent layer of covering varnish.

 The constitution and application of a protective coating against corrosion and wear on the other side of the core layer or of the sheet of soft metal or of soft metal alloy can be carried out in a similar manner to the application, explained above, of a print or a print carrier layer. There are also several possibilities for this purpose a) A protective coating against corrosion and wear can be prepared by unilateral application of a layer of sliding varnish on a metal sheet, preferably an aluminum sheet, and then laminate this protective coating prepared on the sheet of soft metal or of soft metal alloy, to the two free metal surfaces. This can be done by joining together, continuously and practically simultaneously, a strip of sheet of soft metal or soft metal alloy forming the core layer, a strip of metallic foil bearing the imprint and the prepared strip of protective coating against corrosion and wear.

b) Another possibility of applying the protective coating against corrosion and wear consists in applying this coating, for example by painting, for example in the form of a layer of sliding varnish, directly on one of the surfaces of the sheet of soft metal or soft metal alloy forming the core layer.

c) It is also possible to apply, for example laminating, a sheet of synthetic material suitable for protection against corrosion and wear, possibly loaded with powdery material increasing the resistance to wear, directly, that is to say without interposition of a metallic carrier sheet, on the sheet of soft metal or of soft metal alloy.

 In another embodiment of the method according to the invention, it is possible to provide, on one of its sides, a strip of laminated material prepared with a core layer of soft metal or of a soft metal alloy, of a sheet metallic laminate as a print carrier layer and on the other side, a laminated or clad sheet of metal such as copper, tin or aluminum, and then continuously provide it, on the free metallic surface of the desired print-carrying layer, by a process of flexography or intaglio printing and continuously coating it, on the second free metal surface, with a sliding varnish with which powdery material is mixed increasing the resistance to wear . You can optionally mix with the sliding varnish, instead of this material or in addition to this material, a colored pigment.

Exemplary embodiments of the invention are explained more precisely below in connection with the drawings in which
Figure 1 shows an enlarged partial section of the laminated material according to the invention, in one embodiment
Figure 2 is an enlarged partial section of the laminated material according to the invention, in a second embodiment
Figure 3 shows detail 3-3 of Figure 1, further enlarged
Figure 4 shows detail 4-4 of Figure 2, still greatly enlarged; and
FIG. 5 represents a diagram of the manufacturing process according to the invention of the laminated material, in a preferred embodiment.

 In the example of FIG. 1, it is a laminated material 10 printed in the form of a strip which is particularly suitable for the manufacture of rolled bottle caps. To this end, the printed laminated material is transformed into a strip 10 in known manner, that is to say that it is cut into capsule blanks. These capsule blanks are rolled up on capsule molds, they are provided with an axial capsule rib, in particular they are clamped and they are provided with a capsule bottom which is applied as an additional element or which is formed starting from the marginal regions of the capsule blank.

 In the embodiment shown in Figure i, the laminated material 10 has a core layer 11 formed of tin or tin alloy. The core layer 11 in this example has a thickness of approximately 60 to 80 μm. On one side, this core layer 11 carries a print carrier layer 12 formed of pure aluminum. The connection between the print-carrying layer 12 and the core layer 1 is produced by a layer of adhesive 13 and more precisely by means of a reactive synthetic material, possibly of a two-component or multi-component adhesive. On the side opposite to the core layer 11, the print carrier layer 12 carries the desired print 14, which is applied by known printing methods, for example flexography or intaglio printing, preferably as a multi-color print, on the surface of the print carrier layer 12. For the protection of the print 14, the latter is still covered with a colorless and transparent covering varnish, resistant to abrasion, as indicated in 15. The thickness of the print-bearing layer 12 in this example is approximately 20 μm. The quantity of covering varnish applied on top of the print 14 is, in the example described, approximately 2 to 15 g / rn 2, for example 5 g / S.

 On the side opposite to printing 14, the core layer 11 carries a protective coating against corrosion and wear, 16, which, in the example of FIG. 1, is formed by a layer of aluminum 17 d '' about 10 µm thick and by a functional layer 18, as will be explained more precisely below in connection with Figure 4. This functional layer has a gangue of synthetic material 21 which is bonded to the surface of the layer of aluminum 17 with application of pressure and heat. The protective coating against corrosion and wear 16 formed from the aluminum layer 17 and the functional layer 18 is bonded, by means of an adhesive layer 19, to the second surface of the core layer 11 .

The same adhesive can be used here as for the adhesive layer 13.

 In the example of FIG. 2, it is a laminated material 20 in which a core layer 11, formed of lead alloy containing about 4% by weight of tin, is connected by rolling to a layer print carrier 12 formed of metal, for example pure aluminum or copper, the thickness of this metallic print carrier layer 12 possibly being approximately 10 to 15 ssum. To the composite strip thus formed comprising the core layer 11 and the laminated print carrier layer 12, the desired print 14 is applied, by a known printing process, for example a flexography or intaglio printing process and then it is covered with a layer of covering varnish 16 as in the example in FIG. 1. The constitution of the layer 12 bearing the imprint 14 and of the layer of covering varnish 15 is shown in enlargement on the Figure 3 for the example of Figure 1. However, the same constitution also exists in the embodiment according to Figure 2, with the difference that the adhesive layer 13 between the core layer 11 and the carrier layer d printing 12 is eliminated and replaced by a direct metallic bond produced during plating.

 In the example of FIG. 2, the corrosion and wear protection layer 16 is only formed by a functional layer 18 which is bonded by means of an adhesive layer 19 to the surface of the core layer 11, without the interposition of a metal layer.

 As shown in FIG. 4, the functional layer 18 contains a gangue of synthetic material, for example based on polyester or based on polysulfone. In this gangue of synthetic material 21 are embedded the particles of synthetic material 22 increasing the wear resistance, for example cut glass fibers and pigment particles 23. These pigment particles may be suitable preferably for coloring of metals, for example coloring of a tin surface.

 According to FIG. 5, in one embodiment of the method for manufacturing the laminated material, provision is made for doubling on both sides of a sheet 31 of soft metal or of soft metal alloy, for example tin or lead containing about 4% by weight of tin, on one side with a printing medium 32 and on the other side with a protective coating against corrosion and wear 16.

To this end, the soft sheet 31 is brought from a reel 33, passing through a gluing station 34 where it is coated on both sides with a reactive adhesive, for example a two-component adhesive, to the doubling station 35 where it is simultaneously doubled with the printing medium 32 and the protective coating against corrosion and wear 16. The doubling could also be carried out separately, with or without winding and intermediate storage of the lined sheet 31 on the one hand.

 To form the printing medium 32, one starts with a harder metal sheet about 7 to 40 μm thick, preferably of pure aluminum. It is also contemplated using a relatively soft copper foil or aluminum alloy sheet. In this example, the metal sheet 36 is passed through a surface forming station 37 where a desired surface structure is formed in the metal sheet 36, for example by rolling. However, it is also possible, as desired, to use directly for printing a glossy surface originating from the manufacturing process of the metallic foil 36 or else a matt surface originating from the manufacturing process of the metallic foil 36. After the surface forming station 37, the metal sheet 36 passes through a surface cleaning station 38 to then arrive at the printing station 39. This printing station 39 may include a known multi-color printing machine which operates for example according to the flexography process or intaglio printing. After drying the desired printing, produced by this known printing process, the printed metal sheet 36 is passed through a coating station 40 where the printing is provided with a transparent covering layer, for example an abrasion-resistant covering varnish, for example a PVC-based covering varnish. The amount of coating is about 2 to 15g / µm.

 In the example of FIG. 5, the printing medium 32 thus produced is brought directly to the doubling station 35 for the meeting with the lead sheet 31. However, as indicated by the dashed line at 43 in FIG. 5, one could also first wind the finished print medium 32 and store it for later lamination on the soft sheet 31 of lead, tin, lead alloy or tin.

To form the protective coating against corrosion and wear 16, one starts, in the example of FIG. 5, from a metal sheet 41, preferably from soft aluminum alloy. This strip-shaped metal sheet 41 is continuously passed through a coating station 42 where the functional layer formed of a mixture of synthetic material, for example polyethylene, polyester or polysulfone, is applied with material pulverulent increasing the resistance to wear and the pigment, on one side of the metallic foil di and it is bonded and consolidated thereon. In the example of FIG. 5, the protective coating against corrosion and wear in two layers 16 is led directly to the lining station 35 for application to the sheet 3
However, as indicated in dotted lines in FIG. 5 at 44, it is also possible to wind the re-7etemlent strip for protection against corrosion and wear thus prepared and store it for lamination on a sheet 3i. -
However, in the context of the invention, it is also possible to envisage modified processes for the manufacture of synthetic material. For example, the sheet 31 could be joined beforehand to a metal sheet, for example by plating it. it would then be necessary to pass this composite strip, as a whole, through the surface forming station 37, the surface cleaning station 38! the printing station 39 and the coating station 40. Instead of the lining station 35, it would then be necessary to provide a second coating station 42 where it would still be necessary to coat the printed composite strip, on its lead-free surface, with a functional layer of synthetic material for protection against corrosion and wear. According to another variant, it could also, while maintaining the remainder of the procedure described above, starting from a sheet in the form of a strip 31, of lead, tin, lead alloy or tin, doubled at two sides of sheets of another metal.

Claims (20)

 1.- Laminated material for packaging, in particular for the manufacture of bottle caps, the core layer of which is formed of soft metal or of soft metal alloy and carries on at least one side a layer of harder metal or harder metal alloy, material characterized by a strip of printed synthetic material having a core layer (11) of about 20 to about 100 thick formed of the soft metal or the soft metal alloy and a carrier layer of printing (12) applied to one side of this core layer (11) and which is formed from a sheet of harder metal or harder metal alloy, of less thickness than the core layer (11 ) and which has at least on the side opposite the latter a smooth surface on which is applied the impression (14) in question.  2.- Material according to claim 1, characterized in that the print-carrying layer (12) is formed from an aluminum foil or aluminum alloy of about 7 to about 40 µm thick and the layer of core (11), tin or lead or a metal alloy, the essential constituent of which is tin or lead.  3.- Material according to claim 1, characterized in that the print carrier layer (12) is formed of a sheet of copper or copper alloy of about 10 to about 50 µm thick and the layer of core, tin or lead or a metal alloy having tin or lead as an essential constituent.  4.- Material according to one of claims 1 to 3, characterized in that the metal sheet forming the print carrier layer (12) is connected to the core layer (11) via a layer adhesive (13).  5.- Material according to claims 1 and 2 characterized in that the core layer (11) carries, on the side opposite to the print carrier layer (12), a protective coating against corrosion and wear ( 16).  6.- Material according to claim 5, characterized in that the protective coating against corrosion and wear (16) has a carrier layer in the form of a metal sheet, which carries, on the side opposite to the core layer, a functional layer (18) with a layer of synthetic material.  7.- Material according to claim 5, characterized in that the protective coating against corrosion and wear (16) has a functional layer (18) with a gangue of synthetic material, applied directly to the surface of the layer of heart (11).  8.- Material according to one of claims 6 and 7, characterized in that the gangue of synthetic material of the functional layer (18) is formed of sliding varnish and that in this gangue of synthetic material are embedded particles ( 23) increasing the resistance to wear of the functional layer (18), which can at the same time constitute pigment particles for a metallic coloring, for example a copper or tin color.  9. A method of manufacturing the laminated material according to one of claims 1 to 8, characterized in that a prefabricated sheet of soft metal or of soft metal alloy, such as lead, a lead alloy, is coated, tin or a tin alloy, having a thickness of about 20 to about 100 µm, of a sheet of harder metal such as aluminum, an aluminum alloy, copper, a copper alloy having a thickness of about 7 to about 50 μm and that this metal sheet is provided, on its exposed side, by a flexography or intaglio printing process, with the desired impression.  10.- A method of manufacturing the laminated material according to claim 9, characterized in that in the case where a sheet of the harder metal having a shiny surface and a matt surface is used, this metal sheet is connected to its side with the mat surface, with the sheet of soft metal or soft metal alloy and on its side with the shiny surface, it is provided with the desired impression.  11.- Method according to one of claims9 and 10, characterized in that the printing is applied to the metal sheet forming the print carrier layer before joining by doubling this metal sheet to the sheet of soft metal or soft metal alloy forming the core layer, using adhesive.  12.- A method according to claim 11 characterized in that the union of the sheet of soft metal or soft metal bond forming the core layer aa printed metal sheet is effected by continuous bonding of two bands, for example d about 0.9 to 1.0 m from @@ eur.  13.- The method of claim 9, characterized in that it provides the desired impression, -a flexography or printing process, is hollow strip of laminated material preformed by lining plating provided with thicker layer of soft metal of soft metal alloy and a thinner layer of harder metal, at the exposed surface of the thin, harder metal.  14.- Method according to one of claims characterized in that 1 forms the metal layer thinner and harder lique starting from aluminum c of an aluminum alloy, or copper or an ac of copper and that at the latest before printing n lu i gives a chosen surface constitution.  15.- Method according to one of claims 9 to 14, characterized in that when printing on the metal foil or metal layer forming the printing medium, a transparent abrasion-resistant covering layer is applied , preferably a transparent layer of covering varnish.  16) Method according to one of claims 9 to 15, characterized in that is joined to the sheet of soft metal or soft metal alloy forming the core layer, on its metal surface, by doubling with use of adhesive, a protective coating against corrosion and wear prepared by unilateral application of a layer of sliding varnish on a metal sheet, preferably an aluminum foil or aluminum alloy.  17.- Method according to one of claims 11 and 16, characterized in that one joins together continuously and practically simultaneously a strip of sheet of soft metal or of soft metal alloy such as tin, an alloy of tin, lead or a lead alloy forming the core layer1 a strip of metallic foil bearing the imprint and a prepared strip of protective coating against corrosion and wear.  18.- Method according to one of claims 9 to 15, characterized in that the protective coating against corrosion and wear is formed by direct application of a layer of varnish sliding on one of the surfaces of the sheet of soft metal or soft metal alloy forming the core layer.  19.- Method according to claim 9, characterized in that one continually doubles on its exposed metal surface a sheet in the form of a strip of soft metal or of soft metal alloy provided on one side with a protective coating against corrosion and wear, with a metal sheet printed in the form of a strip.  20.- Method according to claim 9, characterized in that one continuously provides a desired printing, by a flexography or intaglio printing process, on the free side of the print carrier layer, a strip of laminated material prepared with a core layer of soft metal or of a soft metallic alloy, with a metallic foil applied by lining or plating on one side as a print-bearing layer, such as a sheet of copper or aluminum or of aluminum alloy and a sheet of metal such as copper, tin or aluminum applied on the other side by doubling or plating.