Method for Producing a Metallic Coating in Certain Areas a Substrate, Transfer Film, and Use Thereof

Abstract

The invention concerns a process for the production of a region-wise metallization on a carrier substrate, wherein the carrier substrate is at least region-wise provided with a soluble colored first layer which on its side remote from the carrier substrate is provided over its full area with a metal layer, as well as a transfer film with a region-wise metalization and the use thereof.

Description

FIGS. 1 a through 3 are intended to describe the process according to the invention and the structure of a transfer film according to the invention by way of example. In the drawing:

FIG. 1 a shows a view in cross-section of a carrier substrate with a first layer, a second layer and a metal layer,

FIG. 1 b shows the carrier substrate of FIG. 1a after dissolution of the second layer and unhardened regions of the first layer,

FIG. 2 a shows a view in cross-section of a further carrier substrate with a first layer, a second layer, a third layer and a metal layer,

FIG. 2 b shows the carrier substrate of FIG. 2a after dissolution of the second layer and unhardened regions of the first layer, and

FIG. 3 shows a view in cross-section through a transfer film in the form of a hot stamping film with region-wise metallization.

FIG. 1 a is a view in cross-section of a carrier substrate 1 which is in the form of a carrier film and which is coated with an alkali-soluble colored lacquer based on styrene maleic acid anhydride (SMA) as the first layer 2.

The lacquer for forming the first layer was of the following composition:

ethanol                          3200 g
ethylacetate                     3100 g
n-butanol                        100 g
SMA resin (mw about 200000, acid No about 250) 1000 g
alcohol-soluble cellulose nitrate (norm 30 A) 100 g
complex dyestuff orange          85 g
complex dyestuff yellow          38 g
aziridin hardener                25 g

In that case the carrier substrate 1 of PET is of a thickness of 25 μm and the first layer 2 is of a thickness of 1 μm. In that case the first layer 2 can be applied to the carrier substrate 1 over the full surface area or only partially. In the present case the first layer 2 contains an aziridin-based hardener. It is possible to provide between the carrier substrate 1 and the first layer 2, further lacquer layers, reflecting layers or other layers which for example can have magnetic properties. A water-soluble, strongly alkaline printing ink is partially applied to the first layer 2 as the second layer 3, the second layer containing sodium hydroxide as an additive and being 1.5 μm in thickness. Titanium oxide is added to the printing ink in order to obtain a well visible and controllable printing result.

The printing ink for forming the second layer was of the following composition:

water                           9200 g
methylcellulose (low-molecular) 750 g
silica highly dispersed         150 g
titanium dioxide (rutile type)  2000 g
ethanol                         1000 g
n-butanol                       600 g
soda lye (50 percent)           2000 g

A mirror-reflecting metal layer 4 of aluminum which is of a thickness of 40 nm covers the second layer 3 and the regions which are uncovered thereby of the first layer 2. The sodium hydroxide of the second layer 3 inactivates the hardener in the first layer 2 in the regions in which direct contact was produced between the first layer 2 and the second layer 3.

FIG. 1 b shows the carrier substrate 1 of FIG. 1a after dissolution of the second layer 3 and non-hardened regions of the first layer 2 in water. It is only in the regions of the first layer 2, which were not covered by the second layer 3, that the hardener became active and resulted in hardening of the first layer 2. Accordingly those regions remain on the carrier substrate 1 including the regions of the metal layer 4, which are disposed directly thereon and which are in accurate register relationship, while the unhardened regions of the first layer 2 and the regions of the metal layer 4 which were arranged on the second layer 3 were removed.

FIG. 2 a shows a further carrier substrate 1 with a water-soluble styrene maleic acid anhydride-based first layer 2 as shown in FIG. 1a, which is applied to the full surface area thereof and which includes an aziridin-based hardener. The first layer 2 is colored and transparent. A water-insoluble, colored-transparent third layer 7 is applied partially to the first layer 2.

The water-insoluble lacquer for forming the third layer was of the following composition:

methyl ethyl ketone              2600 g
PMMA (high-molecular, Tg 120° C.) 500 g
toluene                          2000 g
ester-soluble cellulose nitrate (norm 34 E) 1000 g
cyclohexanone                    300 g
complex dyestuff red             45 g

In that respect a water-soluble second layer 3 which is formed from a strongly alkaline printing ink as shown in FIG. 1a is arranged partially on the third layer 7 and partially on the regions of the first layer 2 which are uncovered by the third layer 7. As an additive the second layer 3 contains sodium hydroxide which inactivates the hardener in the first layer 2 in the regions which are in direct contact therewith. The second layer 3 however does not have an effect on the third layer 7 so that the third layer 7 forms a barrier layer for the sodium hydroxide of the second layer 3. A closed metal layer 4 of chromium covers the second layer 3, parts of the first layer 2 and parts of the third layer 7.

FIG. 2 b shows the carrier substrate 1 of FIG. 2a after dissolution of the second layer 3 and non-hardened regions of the first layer 2 in water. What remain on the carrier substrate 1 are regions of the first layer 2 in accurate register relationship with regions of the metal layer 4, uncoated regions of the third layer 7 and regions of the third layer 7 which are covered with regions of the metal layer 4. A wide range of different effects can be achieved by varying the arrangement of the individual layers.

FIG. 3 shows a cross-section through a hot stamping film 10 with region-wise metallization. Disposed on a carrier substrate 1 in the form of a carrier film is a wax-like separation layer 5 which facilitates detachment of a transfer layer arrangement 9 from the carrier substrate 1 onto a material to be stamped upon. Arranged on the separation layer 5 is a colorlessly transparent, insoluble lacquer layer 8 on which regions of the first layer 2 and the metal layer 4 as formed in FIG. 1b are arranged. An adhesive layer 6 is disposed on the side of the transfer layer arrangement 9 which is remote from the carrier substrate 1. The adhesive used is preferably a hot-sealable adhesive. In the hot stamping operation the hot stamping film 10 is pressed under the effect of temperature with the adhesive layer 6 against the material to be stamped upon and the transfer layer arrangement 9 is transferred entirely or in region-wise manner, for example in the form of patterns, alphanumeric characters or images. The carrier substrate 1 is separated from the regions of the transfer layer arrangement 9, which have been transferred onto the material to which the hot stamping film has been applied. The colorlessly transparent lacquer layer 8 now forms the surface of the transferred regions of the transfer layer arrangement 9 and protects the layer portions arranged therebeneath, for example from damage or manipulative alteration.

The layer systems illustrated in the Figures can be supplemented by further transparent or opaque layers, in which respect various effects can be produced. Multiple application of the process according to the invention in succession to a carrier film, wherein barrier layers can be deliberately used to prevent an additive becoming effective in given regions or layer planes, is also possible. Furthermore the first layer 2 can be formed from two or more colored, transparent, soluble lacquer layers. It is also possible to use opaque colored layers for structuring or a metal layer which is formed in region-wise manner from metals of differing color. That affords innumerable possible variations which the man skilled in the art will recognize as being embraced by the concept of the invention.

Claims

1. A process for the production of a region-wise metallization on a carrier substrate, wherein the carrier substrate is at least region-wise provided with a soluble colored first layer which on its side remote from the carrier substrate is provided over its full area with a metal layer, the process comprising: a) at least partially arranging at least one soluble second layer between the first layer and the metal layer, orb) at least partially arranging at least one insoluble third layer region-wise on the side of the first layer which is towards the metal layer and applying a soluble second layer at least partially to the side of the third layer which is towards the metal layer and partially to the regions of the first layer which are free of the third layer,wherein in cases a) and b) a hardener is added to the first layer and an additive is added to the second layer, which additive is suitable for inactivating the hardener of the first layer, wherein the at least one third layer which is provided in case b) is impenetrable to the additive,the additive of the second layer inactivates the hardener of the first layer in the regions of the first layer which are arranged in direct contact with the second layer before the first layer is hardened by the hardener, andthe second layer and the regions of the first layer in which the hardener was inactivated are dissolved and removed by means of at least one liquid, wherein the metal layer is removed in the regions which were arranged directly on the second layer.

2. A process as set forth in claim 1, wherein the first layer is formed by an alkali-soluble lacquer, preferably based on polyacrylic acid or styrene maleic acid anhydride.

3. A process as set forth in claim 2, wherein a water-soluble dyestuff is added to the alkali-soluble lacquer.

4. A process as set forth in claim 1, wherein the hardener is selected on an aziridin basis or polyimine basis and that the second layer is formed from a water-soluble alkaline printing ink with a pH-value in the range of between 11 and 14.

5. A process as set forth in claim 4, wherein the printing ink is of an alkaline nature by means of sodium hydroxide or potassium hydroxide as additive.

6. A process as set forth in claim 4, wherein the printing ink is mixed with a coloring filler or pigment.

7. A process as set forth in claim 6, wherein barium sulfate, titanium oxide or zinc sulfide is added to the printing ink.

8. A process as set forth in claim 1, wherein the at least one third layer is of a colored opaque and/or colored transparent nature.

9. A process as set forth in claim 1, wherein the at least one liquid contains water or consists of water.

10. A process as set forth in claim 1, wherein a flexible film material is used as the carrier substrate.

11. A process as set forth in claim 10, wherein the carrier substrate is transported from roll to roll to produce the region-wise metallization.

12. A process as set forth in claim 1, wherein the metal layer is of a reflecting and preferably mirror-reflecting nature.

13. A process as set forth in claim 1, wherein the metal layer is formed from one of the metals aluminum, chromium, copper, nickel, iron, titanium, silver, gold or an alloy of two or more of those metals.

14. A process as set forth in claim 1, wherein the metal layer is formed by vapor deposition or cathode sputtering.

15. A transfer film, in particular a hot stamping film, which includes a carrier substrate and a transfer layer arrangement with a region-wise metallization, which can be produced in accordance with claim 1, wherein the carrier substrate is in the form of a carrier film and the transfer layer arrangement has at least one region-wise arranged, colored, first layer and a metal layer arranged in coincident relationship with the first layer, as region-wise metallization, characterized in that the first layer is hardened by means of an aziridin-based or polyimine-based hardener, wherein the first layer as viewed over the layer thickness thereof is hardened uniformly.

16. A transfer film as set forth in claim 15, wherein the first layer is formed by an alkali-soluble lacquer, preferably based on polyacrylic acid or styrene maleic acid anhydride.

17. A transfer film as set forth in claim 16, wherein the alkali-soluble lacquer contains a water-soluble dyestuff.

18. A transfer film as set forth in claim 15, wherein the metal layer is formed from one of the metals aluminum, chromium, copper, nickel, iron, titanium, silver, gold or an alloy of two or more of those metals.

19. A transfer film as set forth in claim 16, wherein the metal layer is of a reflecting and preferably mirror-reflecting nature.

20. A transfer film as set forth in claim 15, wherein the first layer is formed from one or more transparent layers.

21. A transfer film as set forth in claim 15, wherein the carrier film and/or the transfer layer arrangement are at least partially transparent.

22. A transfer film as set forth in claim 15, wherein the transfer layer arrangement includes at least one colored-opaque or colored-transparent third layer.

23. A transfer film as set forth in claim 15, wherein a wax-like separation layer is arranged between the carrier film and the transfer layer arrangement.

24. A transfer film as set forth in claim 15, wherein the transfer layer arrangement has an adhesive layer, wherein the adhesive layer is arranged at the side of the transfer layer arrangement (11) which is remote from the carrier film.

25. Use of a transfer film as set forth in claim 15 for forming security elements on data carriers, in particular value-bearing documents such as identity cards or passes, cards or bank notes, structural elements or decorative elements, in particular in architecture or other technical areas, packaging materials, in particular in the pharmaceutical or foodstuffs industry, or components in the electrical engineering or electronic industry.