CZ81199A3 - Process for producing visually contrast areas on metallic substrate, the metallic substrate per se and use thereof - 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

The present invention relates to metal substrates with visually contrasting surfaces which are suitable, for example, for the production of containers such as beverage cans and the like.

BACKGROUND OF THE INVENTION

At present, the following process is used to create two-color logos, labels and the like on metal substrates: Two epoxy resin coatings of different colors are applied one after the other to the metal substrate. The upper layer is then completely removed by laser ablation so that the lower layer of lacquer contrasting in color remains visible in those areas in which the topcoat has been evaporated.

This process is expensive because the metal substrate must be provided with a double coating resin in separate duty cycles. This is a rather slow and lengthy process, for example when a metal substrate in the form of a plate or sheet is to be coated. This is because the devices used for coating must be continuously cleaned between the application of each differently colored layer, and that the application of the second layer requires interruption of the continuous production process at this time, which greatly reduces the capacity of the production line. However, to date there has been no other way of applying the two differently

77203 (77203a.doc) of epoxy-type resin varnish coatings on a metal substrate if the production was to be carried out on a larger scale.

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SUMMARY OF THE INVENTION

It is an object of the invention to provide a process faster and cheaper compared to the above process, and suitable for large-scale production.

This object is achieved by coating the metal substrate with only one color layer and partially, ie in the desired areas, by removing (evaporating) the layer incompletely by laser irradiation. Surprisingly, it has been found that treating the layer with a laser beam whose energy is lower than that of the prior art results in incomplete removal of the coating. The thin transparent skin or film that remains is considerably thinner than the lacquer layer. Since this shell is surprisingly translucent, the color of the metal substrate becomes visible so that visual contrasts occur.

BRIEF DESCRIPTION OF THE DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be explained in more detail with reference to the drawings, in which: FIG. 1 represents the method according to the invention and the resulting product;

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Examples of examples

Figure 1 schematically illustrates the method of the invention and the resulting product. The metal substrate 1 is fully coated with the color layer 2 prior to laser ablation (A). After evaporation of the color layer, a transparent layer 2, shown in Figure 1B, remains substantially thinner than the original color layer in the laser-impinging areas 4.

In contrast, Figure 2 illustrates a known method mentioned in the preamble, in which under the (first) color layer 2 'of the metal substrate 1' comprises a second, differently colored layer 2 ', which is applied directly to the substrate (A ^1). It follows from Figure 2B that the impact of the laser beam causes complete evaporation of the first in the contact areas, while most of the second color of the second layer 2 'of the layer 2' is retained in the color layer, so that the areas 4 'are visible to the observer.

The thickness of the colored layer can be chosen essentially freely and is determined by common reasons (abrasion resistance, cost, etc.). While in the previously known methods, the thickness of the lower color layer was 3-4 µπι and the upper layer was therefore thinner (e.g. about 0.5 to 2 gm), the thickness of a single color layer according to the invention may be, for example, equal or lesser (e.g. about 2 to 4 gm) , preferably less than 3 gm) compared to what was customary in known methods. The effect of laser ablation remains a considerably thinner layer (e.g. having only a 1/6 to 1/3 thickness), for example when a layer having a thickness of 3 gm is treated by laser ablation, a transparent layer having a thickness of about 0.6 gm can be obtained.

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In the method of the invention, laser ablation can be carried out by conventional methods. Laser ablation is performed, for example, by using a mask or template that covers or reveals letters, words, logos, characters, and the like, or by a printing method, e.g., a dot matrix form. The energy to be generated can be easily calculated by a person skilled in the art, depending on the layer thickness. Of course, higher energy will lead to greater ablation. When the prior art topsheet is compared to a single layer of the present invention, the energy to be generated is clearly lower than that used in the prior art, where the layers have the same thicknesses. Therefore, an NO laser is sufficient to carry out the process of the invention. The adjustment is adjusted so that a larger portion (as described above) of the color layer is removed from the exposed areas and the remaining skin becomes transparent in these areas, so that the metal substrate appears as a second color, and the printing appears bicolour.

The fact that the remaining transparent layer is preserved by the method of the invention can be easily demonstrated by experiments in which the substrates produced are treated with copper sulfate.

The only color layer may be a conventional lacquer, for example an epoxy-type resin. There is no limitation on colors, and dark colors are particularly suitable for better contrast with a metal translucent substrate (eg aluminum, steel).

Because laser ablation in the process according to the invention does not completely evaporate the exposed areas

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colored layers, the remaining thinner and colorless layer (skin) acts as a protective layer protecting the metal from atmospheric influences, and / or a contact barrier against any other substances that can attack the metal and thus also as a corrosion protection.

The newly coated metal sheets may be manufactured in a simple manner by the method of the invention. The boards are anticorrosive and also have an attractive graphic form. In addition, the method can be used to produce two-dimensional metal substrates, and the method is also suitable for producing metal containers such as cans that are either dyed according to the invention after molding or made from metal sheets treated according to the invention. Any specific areas of containers or cans may be processed according to the invention, for example, the bottom and / or the tab. For example, the back of the handle may be provided with a very small mark, which serves as an identification or the like for the manufacturer or the persons skilled in the art.

Claims (10)

A method for producing visually contrasting structures on a metal substrate, characterized in that the substrate, which is coated with a single color layer, is partially subjected to the energy of the laser beam such that a transparent remainder of the layer is maintained in the treated area. The method of claim 1, wherein the colored layer comprises an epoxy type resin lacquer. Method according to claim 1 or 2, characterized in that the areas of the coated substrate which are not subjected to the laser beam are masked. 4 4 44444 4 4 4444 444 44 44445 4 4 4 4 4 4 4 4 4 4 4 4 4 44 4 4 4444 44 4 4444 Method according to claim 1 or 2, characterized in that ablation with the laser beam is performed by means of dot matrix printing. 5. A metallic substrate having visually contrasting structures, characterized in that a portion of the substrate has a single color layer, while on the remaining portion of the substrate there is a single transparent layer that is substantially thinner compared to a single color layer. The metal substrate of claim 5, wherein the single color layer is an epoxy type resin lacquer. 16 77203 (77203a.doc) The metal substrate of claim 5 or 6, wherein the transparent layer, which is substantially thinner than the color layer, has been prepared by exposing a single color layer to light of a laser beam. Container, at least partially consisting of a metal substrate according to any one of claims 5 to 7. A beverage can, at least partially consisting of a metal substrate according to any one of claims 5 to 7. 10. Can for beverages including the handle, which at least partly consists made of metal substrate according to any of claims 5 to 7. 11. Can on beverages according to claim 10, characterized by that the only color layer is at least on the back hand tab, and by j ediná transparent layer it is only on the back of the ear. Represented by: