Method for producing a pattern in relief in a thin plastic card

1. A process for producing a relief pattern in a thin plastic card, the process comprising:

producing a superposition of layers comprising, in order:

a transparent layer,

a stacked layer configured to change under the effect of a laser beam, the stacked layer comprising a stack of hundreds of reflective optical films alternating a film having a high reflectance index and a film having a low reflectance index,

a black surface, and

a substrate layer; and

drawing, using a laser, said pattern through the transparent layer.

2. The process as claimed in claim 1 , wherein said stacked layer comprises at least two layers the thermal expansion coefficients of which are different.

3. The process as claimed in claim 2 , wherein the thermal expansion coefficients have at least a ratio of 1 to 10.

4. The process as claimed in claim 1 , wherein the relative thicknesses of said reflective optical films are set so as to form a quarter-wave interference filter.

5. The process as claimed in claim 4 , wherein said stacked layer is formed by coextruding the reflective optical films.

6. The process as claimed in claim 1 , wherein the black surface is formed by a black printing on a facing surface, facing the stacked layer, of a substrate layer that is not black.

7. The process as claimed in claim 1 , wherein the black surface is formed by a facing surface, facing the stacked layer, of a substrate layer the bulk of which is colored black.

8. The process as claimed in claim 1 , wherein the laser comprises a YAG laser using a wavelength of 1064 nm.

9. The process as claimed in claim 8 , wherein the laser functions in a pulsed mode and with vector-type graphical elements.

10. The process as claimed in claim 9 , wherein the power of the laser is comprised between 5 and 30 W.

11. The process as claimed in claim 10 , where the power of the laser is comprised between 10 and 20 W.

12. The process as claimed in claim 8 , wherein the power of the laser is comprised between 5 and 30 W.

13. The process as claimed in claim 12 , where the power of the laser is comprised between 10 and 20 W.

14. A card made of plastic configured to be subjected to a laser beam, the card comprising:

a transparent layer;

a stacked layer configured to change under the effect of a laser beam and thereby form a relief pattern, the stacked layer comprising a stack of hundreds of reflective optical films alternating a film having a high reflectance index and a film having a low reflectance index,

a black surface; and

a substrate layer.

15. The card made of plastic as claimed in claim 14 , further comprising a relief pattern produced by a laser through the transparent layer.