GB2191460A - Discouraging theft and unauthorised smelting of metal containers - Google Patents

Abstract

A metal container, especially an aluminium beer keg, has a foreign substance applied to its outer surface so as visibly to alter the appearance of the container as a warning to an intending thief, the foreign substance being one which, if the container is heated to a melt-down temperature will disrupt the melting process or degrade the quality of the resultant melt. Various substances may be used as a visible protection, including metals eg zinc, tin, lead, iron, antimony, chromium, titanium or zirconium applied by arc spraying for contaminating the melt and plastics substances, eg polyesters, polyamides, polyurethane or polysulphides, which will damage the smelting component and/or emit fumes. A plastics coating (5), forming a coding band, may be applied by spraying or brushing in combination with a zinc coating (7), and also a logo (9) of polysulphide material may be applied to an aluminium beer keg. A rubber sheet may be applied to aluminium by being steam cured after application or a rubber coating can be bonded adhesively. Other foreign substances applied may be exothermic powders cementitious compounds, or granular or powdered material embedded in the outer surface of the container by blasting. <IMAGE>

Description

SPECIFICATION Improvements relating to containers Field of the Invention This invention concerns containers and in particular metal beer canisters usually referred to as kegs.

Background to the Invention It is now common to transport and store beer and other alcoholic drink to be served on draught in aluminium kegs. In one popular size of keg up to 10kg of aluminium alloy is employed and the theft and unauthorised smelting of the stolen kegs has now assumed a problem of some considerable magnitude. To this end it is an object of the present invention to provide a visible improvement to such kegs which will considerably reduce the attraction of the keg to a potential thief or unauthorised smelter.

Summary of the Invention According to one aspect of the present invention there is provided a method of discouraging the theft and unauthorised smelting of metal containers, typically although not exclusively aluminium beer kegs, in which at least one foreign substance is applied to the surface of the container so as to alter the appearance of the container, which substance on being heated to the temperatures required to melt the basic material from which the container is made will disrupt the melting operation or degrade the quality of the resultant melt or a material made therefrom, or both.

For example, the material could disrupt the melting process by producing a large quantity of coloured smoke, and/or noxious fumes and/or destroy or degrade the vessel in which the melting operation is being carried out.

The foreign substance may degrade the quality of the melt or a substance produced from it by contaminating it with other metals or metal oxides which will render the melt of significantly reduced value in its contaminated form.

The foreign substance may be a material which will show up on spectroscopic analysis, produce visible changes in the colour of the melt and any ingots produced therefrom, or affect the physical properties such as the grain size, brittleness of the melt material when cast.

Alternatively or in addition a foreign material may generate significant volumes of coloured smoke, noxious gases or vapours as the temperature of the keg is increased towards the melting point of the basic material or produce a violent reaction as an exothermic reaction with the molten material in the melt.

Where the basic material is aluminium the foreign material may for example be another metal. Examples of such other metals, and suitable amounts in wt %, are: Zinc 1%; Tin 0.1%; Lead 0.1%; Iron 0.4%; Antimony 0.05%; Chromium 0.5%; Titanium 0.2%; and Zirconium 0.2%.

Each will produce a different effect. Thus for example the addition of lead reduces the hot and cold workability of the final material.

Chromium produces a gold discoloration in the surface of the final material, etc.

Alternative foreign materials which may also be used with an aluminium keg are exothermic powders such as manganese oxide or ferric oxide, rubber and plastics compounds and cementitious compounds.

Where the object is to generate smoke an exothermic powder and organic dye which on being heated generates coloured smoke may be employed as the foreign material.

Where the foreign material is a metal, a convenient method of applying it is by arc metal spraying. Typically, from 1 to 3 wt % of the foreign material can conveniently be applied by this method. The process is relatively easy and uses relatively cheap portable equipment so that it is suitable as a method of applying foreign materials to existing beer kegs. This process is also advantageous because the substrate (i.e. keg) temperature remains low during the process.

In order to give the treated keg an attractive appearance, the coating applied by the arc metal spraying can be patterned, for example to form a logo. Alternatively, the sprayed coating could be painted over.

A suitable non-metallic foreign material is polyurethane. A coating of polyurethane can be applied by spraying or can be cast. A good adhesion of the coating to aluminium can be obtained, provided that a suitable bonding coat is used. An advantage of polyurethane is that it is very tough and gives good wear assistance. Additionally, the material is available in a range of colours. During a smelting process, polyurethane will cause the copious evolution of dense, toxic smoke.

Other suitable coatings can be formed from polysulphides. These can be applied by spraying or brushing, cure rapidly and do not need a bonding coat. If the polysulphide is combined with an epoxy resin, a tough flexible coating is obtained. However, only a limited range of colours are available. When heated, polysulphides undergo tbermal breakdown and generate dense black smoke and sulphorous fumes.

Plastics coatings may also be used. A dense, adherent coating may be applied by flame spraying, and no intermediate bonding coat is required. A wide range of colours are available. However, the substrate (i.e. the keg) must be pre-heated to promote a good flow of the coating as it is applied. A disadvantage of plastic coatings is that their decomposition products are less noxious than those of alternative caatings. It is believed that the most suitable plastics materials are polyesters and polyamides such as nylon.

Rubber may also be used as a coating material. This can be secured to aluminium by being cured after application, or a previously prepared coating can be bonded adhesively.

On heating, rubber undergoes thermal degradation and produces dense black smoke. This can be enhanced by the use of additives such as carbon black. Additionally, other foreign materials such as metal powders may be incorporated in the rubber coating. A possible disadvantage of rubber coatings is the extended processing time required, especially if the rubber is cured directly on to the keg.

The coatings referred to above may also be used in combination, with one coating being applied over another. In particular, a plastic coating may be aplied over a metal coating.

Where it is desired to apply special materials to achieve a special effect, such as a mixture of a exothermic powder and an organic dye to generate coloured smoke, these materials can be applied by incorporating them into a more convenient coating material such as paint or a mastic, or into one of the coatings listed above.

Applying the foreign material as a coating will often be a convenient method of incorporating it, as it can become a part of the existing routine of painting coloured code bands on beer kegs.

The various coatings and methods of application listed above are examples only, and other materials and application methods are possible. For instance a granular or powdered material could be embedded in the outer surface of the keg by blasting.

Although the materials and method have been described above with reference to an aluminium beer keg, this has been taken as an example only and the present invention is applicable to metal containers generally.

According to another aspect of the present invention there is provided a metal container, typically but not exclusively an aluminium beer keg, to the surface of which at least one foreign substance has been applied so as to alter the appearance of the container which substance on being heated to the temperatures required to melt the basic material from which a container is made will disrupt the melting operation or degrade the quality of the melt or of material formed from the melt.

Embodiments of the invention, given by way of non-limiting example, will now be described with reference to the accompanying drawings, in which: Figure 1 is a schematic view of an alumi nium beer keg to which various foreign materials have been applied as coatings; and Figure 2 is a sectional view of a part of a beer keg showing an arrangement for curing a rubber sheet to the external surface of the keg.

Figure 1 shows a conventional aluminium beer keg having a chine 1 at each end and rolling rings 3 spaced toward either end from the horizontal mid-plane of the keg. Between the chines 1 and the rolling rings 3, the keg has three generally cylindrical surface portions.

The upper and lower surface portions each bear a coloured coding band 5. Normally, such a coding band would be painted on to the keg, but in the present case the bands are formed of a polyurethane coating selected to have the appropriate colours. On authorised smelting of the keg, the polyurethane bands 5 will produce a dense toxic smoke.

The entire central surface portion 7 has been coated by arc metal spraying with zinc, to give a total of about 1% by weight zinc out of the total keg. If the keg is melted down, the resulting aluminium melt will be contaminated by the zinc, which will substantially reduce its market value.

Finally, a logo (indicated schematically at 9) has been applied to the central surface portion 7. This has been formed of a polysulphide material, which will generate dense black smoke and sulphorous fumes if an attempt is made to melt down the keg.

Figure 2 shows a method of applying a rubber sheet to a part of the central surface portion of a keg such as is shown in Figure 1.

The Figure shows a section through a part of the aluminium wall 11 of the keg, which has been deformed to provide the rolling rings 3.

The inside of the keg is to the left in Figure 1 and the outside of the keg is to the right. An uncured rubber sheet 13 is applied to a part of the central surface portion 7 of the keg.

The sheet is then covered by a membrane 15 and the sheet and the membrane are then enclosed in a steam box 17 which is clamped to the outside of the keg.

To cure the rubber sheet 13, the inside of the keg and the steam box are both filled with steam as shown, so that the sheet 13 is both heated and placed under pressure. This heat and pressure cures the rubber sheet 13 in the normal manner. After curing, the application of steam ceases and the steam box and pressurising membrane are removed. Since the rubber sheet 13 has been pressed firmly against the wall 11 of the keg during the curing process, it is securely bonded to the wall.

If an attempt is made to melt down the keg, the rubber sheet 13 will decompose giving off dense black smoke. The smoke can be enhanced by incorporating carbon black in the rubber sheet 13. Alternatively, other materials can be added to the rubber to produce other effects.

In all cases, the foreign material which has been applied to the keg is visible, and depending on the manner in which it has been applied will be more or less obvious. Accordingly, an experienced person at least will be able to see fairly readily that a foreign material has been applied to the keg and that accordingly it cannot be melted down safely and profitably. This will reduce the likelihood of the keg being stolen for unauthorised smelting and sale for scrap.

The present invention may also be combined with the invention of our co-pending application 8610902 in which a foreign substance is provided in a manner so as not to be readily apparent.

Claims (1)

1. A method of discouraging the theft and unauthorised smelting of metal containers, typically although not exclusively aluminium beer kegs, in which at least one foreign substance is applied to the surface of the container so as to alter the appearance of the container, which substance on being heated to the temperatures required to melt the basic material from which the container is made will disrupt the melting operation or degrade the quality of the resultant melt or a material made therefrom, or both.

2. A method according to claim 1, in which, the substance acts to disrupt the melting operation by producing a large quantity of coloured smoke, and/or noxious fumes and/or to destroy or degrade the vessel in which the melting operation is carried out.

3. A method according to claim 1 or claim 2, in which the foreign substance acts to degrade the quality of the melt or a substance produced from it by contaminating it with other metals or metal oxides which render the melt of significantly reduced value in its contaminated form.

4. A method according to claim 1 or claim 2 or claim 3, in which the foreign substance is a material which is revealed on spectroscopic analysis, produced visible changes in the colour of the melt and any ingots produced therefrom, or affects the physical properties such as the grain size, brittleness or the like of the melt material when cast.

5. A method according to any of claims 1 to 4, in which the container material is aluminium and the foreign substance is another metai.

6. A method according to claim 5, in which the foreign substance is any one or more of the following metals, respectively present approximately in the associated weight percent: Zinc 1%; Tin 0.1%, Lead 0.1%; Iron 0.4%; Antimony 0.05%; Chromium 0.5%; Titanium 0.2%; and Zirconium 0.2%.

7. A method according to any of claims 1 to 4, in which the foreign substance, in the case of an aluminum container is an exothermic powder such as manganese oxide or ferric oxide, a rubber and plastics compound and/or a cementitious compound.

8. A method according to any of claims 1 to 7, in which an exothermic powder and organic dye which on being heated generates coloured smoke is employed at least in part, as the foreign substance.

9. A method according to any of claims 1 to 8, in which the foreign substance is a metal, and is applied to the container by arc metal spraying.

10. A method according to claim 9, in which 1 to 3 wt % of the foreign substance is applied by metal spraying.

11. A method according to claim 9 or claim 10, in which the coating applied by the arc metal spraying is patterned, for example to form a logo.

12. A method according to claim 9 or claim 10, in which the coating applied by metal spraying is painted over.

13. A method according to any of claims 1 to 4, in which the foreign substance is polyurethane.

14. A method according to claim 13 in which the polyurethane is applied by spraying or is cast.

15. A method according to any of claims 1 to 4, in which the foreign substance is a polysulphide.

16. A method according to claim 15, in which the polysulphide is applied by spraying or brushing.

17. A method according to claim 15 or claim 16, in which the polysulphide is combined with an epoxy resin.

18. A method according to any of claims 1 to 4, in which the applied foreign substance is a plastics coating.

19. A method according to claim 18 or claim 19, wherein the substrate (i.e. the container) is pre-heated to promote flow of the plastics coating as it is applied.

21. A method according to any of claims 18 to 20, in which the plastics material is a polyester or a polyamide such as nylon.

22. A method according to any of claims 1 to 4, in which the applied foreign substance is rubber.

23. A method according to claim 22, in which a rubber coating is secured over aluminium by being cured after application.

24. A method according to any of claims 5 to 23, having different coatings used in combination, with one coating being applied over another.

25. A method according to claim 24, in which a plastics coating is applied over a metal coating.

26. A method according to any of claims 1 to 4, in which the foreign substance is incorporaed into a convenient coating material such as paint or a mastic.

27. A method according to any of claims 1 to 4, in which the foreign substance is a granular or powdered material embedded in the outer surface of the container by blasting.

28. A metal container, typically but not exclusively an aluminium beer keg, to the surface of which at least one foreign substance has been applied so as to alter the appearance of the container, which substance on being heated to the temperatures required to melt the basic material from which a container is made will disrupt the melting operation or degrade the quality of the melt or of material formed from the melt.

29. A method of discouraging theft and unauthorised smelting of metal containers, substantially as hereinbefore described.

30. A metal container substantially as hereinbefore described with reference to the accompanying drawings.