FIELD OF THE INVENTION This invention relates to the application of a decorative finish to metal surfaces in order to enhance the aesthetic appearance thereof.

BACKGROUND TO THE INVENTION It is an ongoing practice to provide a decorative finish to all sorts of different products in order to enhance the aesthetic appearance and, at the same time, the appeal to the purchaser or user of a product.

One technique that is applied extensively to paper products, such as greetings cards, letterheads, business cards, menus, and numerous other types of printed material, is the application of decorative material to the surface of the paper product by a transfer process with the decorative material itself typically being carried by a releasable layer on a carrier film.

One type of such decorative material is that commonly known as foil, generally termed a hot stamp foil, in which case the decorated zones may have a metallic and shiny appearance, a brightly coloured appearance, a woodgrain appearance, and may be either gloss or matt in finish. Such foils are produced in a wide range of different colours and are generally so thin as not to be self-supporting thus requiring the support of the carrier film prior to application thereof.

On the other hand, the decorating of metal surfaces utilizing such transfer techniques has not been practiced as far as applicant can establish, and, indeed, applicant has been led to believe that it is generally regarded as not being possible to apply such transferred finishes to metal surfaces.

OBJECT OF THE INVENTION It is, accordingly, an object of this invention to provide for the application of such transferred decorative material to metal surfaces in order to enhance the appearance of same.

SUMMARY OF THE INVENTION In accordance with this invention there is provided a method of applying decorative material to the surface of an article wherein the decorative material is carried by a carrier film, the method being characterized in that the surface to which the decorative material is to be applied is a metal surface that has applied thereto a suitable bonding layer to which the decorative material is applied and bonded.

Further features of the invention provide for the decorative material to initially be in the form of a decorative layer that is transferred from a release layer in turn carried by the carrier film in which case the carrier film may optionally be removed after bonding of the decorative layer to the bonding layer has taken place ; for the bonding layer to be a suitably flexible layer permitting of subsequent bending of the metal surface; for the bonding layer to be a suitable plastics material that bonds to metal and that receives the decorative layer as a permanent attachment thereto, the plastics material preferably being a single component polyester based paint or the like ; for the bonding layer to be applied to the metal surface by means of a roller paint applicator; for the layer of bonding material to be dried, cured or otherwise set to a predetermined extent prior to application of the decorative layer thereto; and for the decorative layer to be applied to the exposed surface of the bonding material utilizing heat and pressure.

Still further features of the invention provide for the article to be an elongate metal strip or pre-cut sheet that is preferably passed firstly through a solvent ! P) 500 2002-12-20

bath to clean the surface of the metal preparatory to the application of the bonding layer thereto; for the metal strip or sheet to be a tin plated mild steel, aluminium, or ordinary mild steel ; for the composite decorative film and metal strip or sheet to be passed between a pair of heated rollers in order to bond the decorative material to the surface of the bonding layer ; and for the decorative material to be a hot stamp foil.

In order that the above and other features of the invention may be more fully understood one embodiment thereof will now be described with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:- Figure 1 is a schematic illustration of the process of applying a decorative layer to a strip of tin plated mild steel ; and, Figure 2 illustrates schematically the various layers of material that combine to form the finished article having a decorated surface.

DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS In one embodiment of the invention a decorative foil is applied to the operatively outer surface of a metal strip that is to be subsequently bent longitudinally to form a bead for the purpose of rimming calendars. Of course the actual product produced can vary widely and could, for example, the slats of slatted blinds such as Venetian blinds, book edges, filling strips and any other generally sheet-like metal objects.

In this embodiment of the invention the foil is a hot stamp foil, generally indicated by numeral (1) in Figure 2, and is a composite multilayer material comprising a carrier film (2), typically made of polyester material ; a releasing wax layer (3); and a decorative layer (4) that in this case is a metallic foil of a chosen colour, say gold.

Referring now also to Figure 1, the metal strip (5) that is a tin plate of the type commonly used for the aforesaid purpose, is fed from a coil or roll (6) thereof by way of guide rollers (7) through a solvent bath (8) to remove all grease from the metal. Of course the tin plate could be in the form of pre-cut sheets as may be convenient.

From the solvent bath the metal strip is passed through a rule paint to cater (9) in order to apply a layer of bonding material (10) to what is to be the operatively external surface of the metal strip. In this particular embodiment of the invention the bonding material was a single component polyester based paint that was purchased from Becker Paints in South Africa. Any other suitable paint exhibiting appropriate adhesive characteristics as well as flexibility in instances in which bending of the metal strip is to take place could also be used. It is, however, envisaged that the bonding layer would in any event be a suitable plastics material.

The metal strip the is then passed through a drying unit (11) to dry the bonding layer to a predetermined extent preparatory to the foil being applied to it. The drying unit applies heat indirectly to the bonding layer in order to avoid any solvents from the bonding layer possibly igniting and preferably has an extractor fan. A so-called"camelback"type of tunnel oven has been found to be ideally suited to this application. The oven temperature, in the case that the aforementioned paint is employed as the bonding layer, has been effectively set at 230 degrees centigrade. Curing has been found to take place to an adequate extent in approximately 20 seconds residence time

in the drying unit. Of course the temperature and speed of travel through the oven can be manipulated to achieve desired results in known manner.

The metal foil emerging from the oven has the foil (1) that is supplied from a roll (12) thereof applied to the exposed surface of the bonding layer at an alignment roller (13) so that the alignment roller can remove or avoid the formation of creases in the foil.

The decorative layer of the foil is bonded to the bonding layer by passing the metal strip and foil together between a pair of heated silicon rubber rollers (14). The rollers are typically heated to a minimum of 120 degrees and typically to about 230 degrees centigrade, or even higher. It has been found that rollers having a Shore hardness of approximately 60 operate effectively.

As an alternative, the one roller, typically the lower roller, could be a metal roller.

The heat and pressure has the effect of bonding the decorative layer to the adjacent surface of the bonding layer and simultaneously melting the wax release layer (3) so that the carrier film and wax separate from the decorative layer (4) that becomes permanently bonded to the bonding layer.

The decorated strip or sheet formed in this way can be handled and processed immediately, for example to form said metal strips for rimming calendars all for any other purpose such as those indicated above.

It will be understood that numerous other embodiments of the invention a possible within the scope hereof.