A METHOD TO PRINT DURABLE AND HIGH CONTRAST IDENTIFICATION CODES, INDICIA AND/OR FIGURES ON AN ANIMAL TAG

Abstract

It is disclosed a method to print durable and high contrast identification codes, indicia and figures on an animal tag. The method is characterized by printing an ink on a polymeric substrate of the animal tag, the step of printing being executed with inkjet printing technique and the ink being a UV-curable ink including pigments, wherein the ink is UV cured after inkjet printing, to become integral part of the polymeric substrate.

Claims

1. A method to print durable and high contrast identification codes, indicia and figures on an animal tag, characterized by printing an ink on a polymeric substrate of said animal tag, said step of printing being executed with inkjet printing technique and said ink being a UV-curable ink including pigments, wherein the ink is UV cured after inkjet printing, becoming integral part of the polymeric substrate.

2. The method according to claim 1, wherein the step of printing is executed in a drop on demand mode.

3. The method according to claim 1, wherein the polymeric substrate includes thermoplastics, preferably polyurethane, or nylons, preferably polyamides.

4. The method according to claim 1, wherein the UV-curable ink includes a cycloaliphatic epoxy resin, polymerization of the resin is made through a cationic reaction mechanism and the polymerized resin becomes part of the polymeric substrate once cured by either a LED source or medium-pressure mercury lamp.

5. The method according to claim 1, wherein the UV-curable ink includes epoxy acrylate resin, polymerization of the resin is made through a free radical reaction and the polymerized resin becomes an integral part of the polymeric substrate when UV cured.

6. The method according to claim 3, wherein the polymeric substrate is a thermoplastics or polyurethane based substrate and the UV curable ink is composed of a cycloaliphatic epoxy resin.

7. The method according to claims 3, wherein the polymeric substrate is a thermoplastic or polyamide and the UV curable ink is composed of epoxy acrylate resin.

8. The method according to claim 1, further including the steps of mixing a first and a second UV-curable inks, the first ink being adapted to start a cationic reaction on the polymeric substrate, and the second ink being adapted to start a radical reaction on the polymeric substrate, and wherein said mixing of UV-curable inks is made before said inkjet printing and said UV curing.

9. The method according to claim 8, wherein the first UV-curable ink includes cycloaliphatic epoxy resin and the second UV-curable ink includes epoxy acrylate resin.

10. The method according to claim 1, characterized by further including a corona discharge treatment on said polymeric substrate, said corona discharge treatment being applied before inkjet printing.

11. The method according to claim 1, wherein the pigment characteristics of the pigments included in the ink are selected on the base of polymers of said polymeric substrate.

12. The method according to claim 1, wherein pigments characteristics to be selected include a percentage of pigments in ink volume 2-3% wt, a pigment size preferably less than 100 nm, a hue, a saturation, a lightness of the pigment.

13. The method according to claim 1, wherein pigments are black.

14. The method according to claim 1, wherein pigments size are in a range of nanometers.

15. The method according to claim 1, including the step of applying a varnish on the substrate, the varnish being applied after curing the printed ink.

16. The method according to claim 1, wherein the varnish includes UV stabilizers for improving light fastness.

17. The method according to claim 1 wherein the ink is void of solvent, dyes, resin binder, cross linker or adhesion promotors.

18. The method according to claim 1 wherein said step of UV curing include applying UV light through a UV LED.

19. The method according to claim 1 wherein the animal tag is an animal ear tag.

20. An animal tag comprising a polymeric substrate and durable and high contrast identification codes on the polymeric substrate marked using a pigmented UV cured inkjet printed ink.

21. The animal tag according to claim 20, wherein the UV curable ink include pigments of black color.

22. The animal tag according to claim 21, wherein the pigment of black color is carbon black.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0059] According to the present invention, a method to print durable and high contrast identification codes, indicia or figures on an animal tag, is provided and based on the following steps, which is here described just to give an example on how the method may be implemented and without limiting the scope of protection of the invention.

[0060] The animal tag comprises a plastic substrate, more particularly a polymeric substrate, adapted to be attached to the animal, for instance to an ear of the animal, and to carry on the identification codes, indicia or figures or even barcodes. The information associated to the tag according to the present invention have a good contrast with respect to the underling substrate, are easily detected or read by human operators or an electronic reader, also from a long distance; the same information is durable, at least as long as the life of the animal, and have high resistance to atmospheric agents, such as rain, wind, sun, humidity, maintaining the good contrast also after long exposures to these agents.

[0061] According to the method of the present invention, an ink is printed on the polymeric substrate of the animal tag, on a surface of such substrate intended to be exposed to the sight of the operators or to the readers, a substantially flat surface counter posed to another surface adapted to be in contact with the animal's ear or another portion of the animal.

[0062] The step of printing the ink is executed with inkjet printing technique. This step forms a digital image by propelling droplets of ink onto the surface of the polymeric substrate and is executed through a printer having a print head adapted to deposit droplets directly on the polymeric substrate surface, through a continuous or, preferably, a Drop-on-demand technique, and according to a digital pattern corresponding to the information to be printed.

[0063] Preferably, the polymeric substrate of the animal tag is preliminary treated to improve adhesion of the UV curable ink, for instance through a corona discharge treatment.

[0064] The applicant has discovered that a UV-curable ink including pigments, for instance black pigments, is adapted to give a higher contrast and to guarantee a longer durability on the polymeric substrate than other type of inks, for instance inks containing dyes. More particularly, indicia obtained by printing an ink including black pigments, printed with ink jet printing technique on a polymeric substrate having a yellow or white substrate, is more durable and readable, also after long time exposures to atmospherically conditions, than indicia printed on the same polymeric substrate, also having the same color surface, obtained by printing an ink with dyes.

[0065] UV-curable inks comprise for example acrylic monomers with an initiator package. The printed ink is cured by exposure to UV-light; a chemical reaction takes place where the photo-initiators cause the ink components to cross-link into a solid on the animal tag. For instance a LED lamp or a shuttered mercury-vapor lamp arranged on either side of a print head produces a great amount of heat to complete the curing process. This lamp may be used for instance for a free radical process to cure the UV ink.

[0066] Curing processes with high power for short periods of times (microseconds) allow curing inks on thermally sensitive substrates. Advantageously, UV curable inks do not evaporate but rather cure or set as a result from a chemical reaction, and about 100% of the delivered ink is used to provide coloration, very quickly. This allows a very fast print process of the animal tags, increasing the through put.

[0067] Indeed, advantageously, UV-curable inks dry as soon as they are cured and they produce a very robust visual image (text or figure or bar code, etc) on the animal tag.

[0068] According to the present invention, durability of the indicia on the polymeric substrate is further increased by selecting an ink with pigments which become part of the deposited ink layer, curing the ink after inkjet printing on the polymeric substrate surface fixes the ink layer to the polymeric surface of the tag. The effect of the UV cure is integrating the printed ink on the polymeric substrate, i.e. strengthening the link between the ink and polymeric substrate, at least in the region of the surface of the polymeric surface. This structure is adapted to resist for long time to the sun, to the rain, wind, humidity but also to rubbing of the polymeric surface against other surfaces, since the ink pigment corresponding to the indicia are integrally connected to the surface of the animal tag.

[0069] The pigment is solid and changes the color of reflected or transmitted light as the result of wavelength-selective absorption. The pigments have special properties that make them ideal for coloring the polymeric substrate of the animal tag. The pigment is selected to have a high tinting strength relative to the polymeric substrate it colors, and to be stable in solid form at ambient temperatures, more particularly at the outside temperatures of the environment in which the animal live. Preferably the pigments are carbon-based, for instance made from soot. Advantageously, the carbon particles do not fade over time even when in sunlight and are chemically stable.

[0070] The pigment characteristics of the pigments included in the ink are selected on the base of polymers of the polymeric substrate. Pigments characteristics to be selected include a percentage of pigments in ink volume 2-3% wt, a pigment size preferably less than 100 nm or in the range of nanometers, a hue, a saturation, a lightness of the pigment.

[0071] According to another aspect of the invention, the polymeric substrate of the animal tag may include thermoplastics, preferably polyurethane, or nylons, preferably polyamides.

[0072] In an embodiment of the invention, the UV-curable ink includes a cycloaliphatic epoxy resin, and polymerization of the cycloaliphatic epoxy resin is made through a cationic reaction, this reaction being controlled by the printer, when the UV-curable ink is printed on the polymeric substrate. The polymerized resin becomes part of the polymeric substrate once cured, for instance by either a LED source or medium-pressure mercury lamp.

[0073] In another embodiment of the invention, the UV-curable ink includes epoxy acrylate resin, polymerization of the resin is made through a free radical reaction and the polymerized resin becomes an integral part of the polymeric substrate when UV cured.

[0074] Concerning the animal tag polymeric substrate different material may be used and the UV curable ink selected on the base of the material of the polymeric substrate. For instance, a thermoplastics or nylon based substrate may be used for the animal tag and, in this case, a UV curable ink composed of a cycloaliphatic epoxy resin presents high adhesion properties.

[0075] Differently, when the polymeric substrate of the animal tag is a thermoplastic or polyamide, the UV curable ink is preferred to be composed of epoxy acrylate resin to provide high adhesion on the animal tag substrate surface.

[0076] The applicant has also identified possible mixture of different UV curable ink adapted to be applied on the animal tag with a corresponding chemical reaction. A first and a second UV-curable inks may be mixed, the first ink being adapted to start a cationic reaction on the polymeric substrate, and the second ink being adapted to start a radical reaction on the polymeric substrate, and wherein said mixing of UV-curable inks is made before said inkjet printing and UV curing. The UV cure ends and fixes the chemical reaction (cationic or free radical) ensuring high adhesion of the inks to the tag surface. For instance, the first UV-curable ink includes cycloaliphatic epoxy resin and the second UV-curable ink includes epoxy acrylate resin.

[0077] A step of applying a varnish on the polymeric substrate, after curing the printed ink, is preferably executed to further enhance adhesion properties of the ink to the tag and its color contrast and readability. The varnish may include UV stabilizers for improving light fastness.

[0078] The main advantages of the present invention are briefly resumed here below. The method for printing indicia on the animal tag guarantees a durability of the indicia, a contrast and a resistance to harsh which is definitely increased with respect to durability, contrast and resistance in known laser technique or digital printing techniques commonly used to print on the animal tags.

[0079] The method is a great alternative to more sophisticated and expensive technologies based on laser marking combined with heating and laser overprinting and, at the same time, reduces the manufacturing time due to the speed at which the UV curable ink dry on the polymeric surface of the tag, through UV cure, in absence of solvent or water.

[0080] Advantageously, in the method to print animal tag, no resin binders, cross linkers, adhesion promotors, solvents or other material commonly necessary in other printing techniques are used, avoiding dangerous solvents emissions and requesting the cost and complexity of the process and the corresponding animal tag.