KR100488321B1 - A metallic object provided with areas of contrasting appearance - Google Patents

Abstract

The present invention relates to a process for making visually contrasting structures on a metallic substrate (1), characterized in that the substrate which is coated with a single coloured layer (2) is partially subjected to the energy of a laser beam in such a way that a transparent remainder (3) of the layer is maintained on the treated area; a metallic substrate which is provided with visually contrasting structures, characterized in that a single coloured layer is present on part of the substrate, while on the remaining part of the substrate in place of this layer a single transparent layer which is substantially thinner as compared to the single coloured layer is present; and containers and cans made from the said substrate.

Description

Metal object with visual contrast structure {A METALLIC OBJECT PROVIDED WITH AREAS OF CONTRASTING APPEARANCE}

The present invention relates to a metal substrate having a visual contrast surface suitable for the manufacture of containers such as beverage cans.

The following process is used to create a two-color logo, label, etc. on the metal substrate: two epoxy-type lacquer layers of different colors are applied one by one on the metal substrate, after which the top of the two layers is removed by laser ablation. A lower layer of lacquer can be observed which is completely removed and contrasting in color in the area where the upper lacquer has evaporated.

This process is expensive in that the resin must be provided by coating the metal substrate twice in separate process cycles. For example, when coated in the form of a plate or sheet of a metal substrate, this process is very slow and tedious. This is because the facilities used for coating have to be thoroughly cleaned between the application steps of the differently colored layers and the application of the second layer requires a continuation of the continuous manufacturing process which greatly reduces the capacity of the production line. However, there have been no methods other than applying two differently colored epoxy resin type lacquer layers on a metal substrate when they are produced on a large scale.

1 schematically shows the process and the resulting product according to the invention.

2 shows a process of the prior art.

* Code Description

1 ... metal substrate 1 '... metal substrate

2 ... colored layer 2 '... first colored layer

3 ... transparent layer 4 ... laser beam treatment area

5 '... second colored layer

It is an object of the present invention to provide a process which is faster and cheaper than the above process and suitable for mass production.

This object is achieved by coating only a single colored layer in the required area and partially removing (evaporating) this layer by laser ablation. Surprisingly, it has been found that treating the layer with a low energy laser beam results in partial removal of the coating compared to the prior art. A transparent "skin" or film is left that is much thinner than the lacquer layer. These skins are so transparent that you can see the color of the metal substrate, providing visual contrast.

In FIG. 1, the metal substrate 1 is completely coated with the colored layer 2 prior to laser removal (A). When the colored layer is evaporated, the remaining transparent layer 3, which is much thinner than the original colored layer, appears in the laser beam treatment region 4 (B).

In FIG. 2 the metal substrate 1 'comprises a second colored layer 5' which is applied directly on the substrate under the first colored layer 2 '(A'). Subsequent irradiation of the laser beam completely evaporates the first colored layer in the affected area 4 'so that most of the second layer 5' is retained and the color of the second layer 5 'is changed to the area 4'. Results in what is seen by the observer at (B ').

In principle, the thickness of the colored layer can be freely selected and is determined in consideration of wear resistance, price and the like. In known processes, the thickness of the lower colored layer is usually 3-4 μm and the upper layer is 0.5 to 2 μm thinner, and the thickness of the only colored layer of the present invention is thinner than the known process (eg 2 to 4 μm, especially 3 μm). ). When the layer having a thickness of 3 mu m is processed by laser ablation, a very thin layer (thickness of 1/6 to 1/3) is left, so that a transparent layer having a thickness of 0.6 mu m can be produced.

Laser ablation in the process according to the invention can be carried out according to conventional methods. For example, laser ablation is performed by applying a mask or stencil that covers or exposes letters, words, logos, drawings, and the like, or by printing in dot-matrix form. The energy to be generated can be easily calculated by one skilled in the art depending on the layer thickness. Higher energy, of course, results in greater removal. The energy to be generated when the top layer of the prior art is compared with the monolayer of the present invention is significantly lower than the energy used in the prior art if the layers have the same thickness. Therefore, the use of a NO laser is sufficient for carrying out the process according to the invention. The colored layer is removed from the exposed area, and the remaining skin is transparent in this area, so that the metal substrate can be adjusted in the second color as if two colors were printed.

The fact that the transparent layer is actually maintained by the process according to the invention is demonstrated by experimenting with a substrate treated with copper sulfate.

The single colored layer may be an epoxy resin type lacquer. There is no limitation as far as color is concerned, and dark colors are particularly suitable as they provide better contrast with metal transparent substrates (aluminum, steel).

Laser ablation in the process according to the invention does not completely evaporate the exposed areas of the colored layer, so the remaining thinner and colorless layer ("skin") is used to protect the metal from atmospheric effects or to attack other metals that attack the metal. Acts as a contact barrier and provides corrosion resistance.

By the process according to the invention a new coated metal sheet can be produced in a simple manner. This sheet has an attractive graphical form and is corrosion resistant. In addition to the production of two-dimensional metal substrates, the process is also suitable for the production of metal containers such as cans made from metal sheets treated according to the invention or "painted" in accordance with the invention after molding. Secondly, certain areas of the container or can (ie bottom or tab) can be treated according to the present invention. Thus, a very small mark can be provided on the back side of the tab which serves as an identification part for the manufacturer.

Claims (11)

In a method of making a visual contrast structure on a metal substrate, And wherein the substrate coated with a single colored layer is partially subjected to laser beam energy such that the transparent portion of the layer remains on the treated area. The method according to claim 1, wherein the colored layer comprises an epoxy resin lacquer. The method of claim 1, wherein the coated substrate area that is not subjected to laser beam energy is covered with a mask. 3. Method according to claim 1 or 2, characterized in that the laser beam removal is performed by means of printing in dot-matrix form. In a metal substrate having a visual contrast structure, A metal substrate, wherein a single colored layer is present on a portion of the substrate and on the remaining portion of the substrate there is a single transparent layer thinner than a single colored layer. The metal substrate according to claim 5, wherein the single colored layer is an epoxy resin lacquer. The metal substrate according to claim 5 or 6, wherein a transparent layer thinner than the colored layer is formed by exposing a single colored layer to the laser beam. Container consisting of a metal substrate according to any one of claims 5 to 7. A beverage can consisting of a metal substrate according to any one of claims 5 to 7. Beverage can including a tab composed of a metal substrate according to any one of claims 5 to 7. 11. The beverage can of claim 10 wherein a single colored layer is present on at least the back side of the tab and a single transparent layer is present only on the back side of the tab.