Patent Application
20070272760
For a better understanding of the present invention, reference will now be made, by way of example, to the following description of the invention and to the accompanying drawings, in which:
In
In a first embodiment, the smart card is intended to use contact pads to communicate with the outside world (
At least one main surface 33B is printed for obtaining a tri-dimensional visual effect, while the other surface 33A may be printed either in a conventional way or in such a manner that it presents also a visual relief aspect. A conventional printing process is made by applying a conventional ink 31 directly on the surface 33A of the core 30 either by means of a silk screen process or by means of an offset process.
For obtaining the required tri-dimensional effect on at least one main surface 33B, the method of printing comprises the step of applying a metallic ink 34 on the whole surface 33B of the core 30 and a second step of coating the metallic ink 34 with a varnish 35. Metallic ink 34 is at least partially coated with the varnish 35, so that the varnish is applied to create inscriptions, such as logo or text, on the surface of the metallic ink. Then, standard overlay layers 32A, 32B are laminated on main printed surfaces 33A, 33B of the core 30.
In a second embodiment, the smart card is intended to use at least radio-frequency waves to communicate with the outside world. In this case, at least one of the main surfaces of the core 30 is coated by an additional printed plastic layer 31A, 31B. Finally, overlay layers 32A and 32B are provided on both main surfaces of the card.
At least one additional printed plastic layer 31B is made for obtaining a tri-dimensional effect. If a second printed layer 31A is provided, it may be printed either in a conventional way or in such a manner that it presents also a tri-dimensional effect. A conventional printed layer 31A is made by applying a conventional ink 31 on a plastic sheet 31A either by means of a silk screen process or by means of an offset process.
For obtaining a relief aspect on the printed layer 31B, the method comprises a first step of applying a metallic ink 34 on the whole surface of the plastic layer 31B and a second step of coating at least partially the metallic ink 34 with a varnish 35.
A standard overlay layer 32B, made of PVC for example, is then applied onto the printed layer 31B and laminated. Preferably, the core 30, the printed layer (s) 31A, 31B and the overlay layers 32A, 32B are joint together by means of a hot lamination process.
In both embodiments, the varnish 35 is preferably applied in a viscous state and then, it is polymerized by means of ultraviolet rays. Moreover, in order to create a relief aspect, the UV varnish is not applied on the whole surface of the metallic ink 34, but it is applied by means of silk screen printing process in order to alternate areas with UV varnish and areas without UV varnish and thus to create a drawing or a text.
The UV varnish is preferably chosen to be transparent in order to preserve the same color on the surface of the card.
One can for example use the UV varnish commercialized by Sericol under the reference UVIVID CN 622.
Preferably, the metallic ink 34 and the UV varnish 35 are applied by means of a silk-screen printing process. The use of a silk screen process is a standard printing process that is currently used in the card manufacturing processes and that is integrated in standard production lines. Consequently, the process for producing a printed smart card with a relief effect is of low cost and there is no extra cost compared to standard silk-screen inks.
Preferably, the mesh used for the silk-screen process is equal to 54. With such a mesh the obtained tri-dimensional aspect is optimum. If the size of the mesh is smaller, for example a mesh 77, then the quantity of ink and varnish applied is not sufficient to obtain a relief effect. On the other hand, if the size of the mesh is higher, the quantity of ink and varnish that are applied is too large so that tri-dimensional effect loses fineness.
In order to obtain a required relief effect with an optimum fineness, the thickness of the applied metallic ink 34 is advantageously comprised between 6 and 12 μm and the thickness of the varnish 35 is comprised between 16 and 24 μm. More advantageously, the thickness of the metallic ink is about 10 μm and the thickness of the varnish is about of 20 μm.
The overlay layer(s) 32A, 32B is a conventional overlay, whose thickness is in the range between 50 μm and 100 μm.
In both embodiments, the tri-dimensional aspect is obtained thanks to the application of the metallic ink 34 followed by the creation of an inscription by means of the varnish 35 applied on the metallic ink, and finally to the hot lamination step. Namely, after the hot lamination of the overlay layer 32B onto the printed surface comprising a metallic ink 34 and an UV varnish 35, the varnish becomes dull while the metallic ink remains brilliant. This difference of aspect between the metallic ink and the inscription made of UV varnish contributes to obtain a tri-dimensional effect. The inscription made of dull UV varnish 35 appears to be engraved in the surface of the card (see
Moreover, the overlay layer 32B allows to erase the existing extra-thickness due to the presence of the inscription made of varnish 35, applied by means of a silk screen printing process on the metallic ink. Thus, the surface of the finished card is flat, while it holds an inscription (drawing and/or text) which appears to be in relief.
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.
