Surface treatment process for a card
The hot stamping method effectively addresses the inefficiencies of existing techniques by creating precise surface roughness variations on cards using a film and die, eliminating the need for additional materials and reducing costs.
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Applications
- Current Assignee / Owner
- IDEMIA FRANCE SAS
- Filing Date
- 2024-12-16
- Publication Date
- 2026-06-19
AI Technical Summary
Existing methods for creating cards with areas of different roughness, such as varnishing and rolling processes, are costly, time-consuming, and lack precision.
A method involving hot stamping a card's surface using a film and a stamping die without adding material, where the die is heated to a specific temperature to soften a portion of the card's surface, altering its roughness while maintaining the other portion unchanged, using a bi-oriented polyethylene terephthalate film.
Achieves precise and cost-effective creation of varying surface roughness on cards without the need for consumables, reducing equipment costs and manufacturing time.
Smart Images
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Abstract
Description
Title of the invention: Method for surface treatment of a card FIELD OF INVENTION
[0001] The present invention relates to a method for surface treatment of a card, to obtain a card having a surface comprising areas of different roughness. PRIOR TECHNOLOGY
[0002] Various techniques exist for obtaining a card with a surface comprising areas of different roughness (for example a matte area and a glossy area).
[0003] A first technique consists of varnishing a card to obtain a glossy area compared to an unvarnished area. However, this solution is not satisfactory, because varnish is a consumable that increases the cost of manufacturing the card.
[0004] A second technique consists of implementing a rolling process using a rolling plate having two different roughnesses. However, this solution has disadvantages: it is costly in terms of consumables, costly in terms of equipment used, time-consuming to implement, and not very precise. Description of the invention
[0005] One object of the invention is to obtain on a map areas of different roughness without suffering the aforementioned disadvantages.
[0006] This objective is achieved by a method for treating the external surface of a card, the external surface comprising a first portion and a second portion, the method comprising hot stamping the first portion so as to vary the roughness of the first portion relative to the roughness of the second portion, the hot stamping being carried out without adding any material to the card, wherein the hot stamping comprises applying a film to the first portion but not to the second portion using a stamping die. The stamping die is heated to a hot stamping temperature, the film is infusible at the hot stamping temperature, and the hot stamping temperature and the film are adapted to cause softening of the first portion.
[0007] The method may also include the following optional features, taken alone or in combination whenever technically possible.
[0008] Preferably, the softening takes place when the first portion reaches its glass transition temperature.
[0009] Preferably, the stamping film or die includes a raised pattern which is imprinted in the first portion of the surface during hot stamping.
[0010] Preferably, the film is made of polyethylene terephthalate. Most preferably, the polyethylene terephthalate is bi-oriented.
[0011] Preferably, the film has a thickness ranging from 8 to 200 micrometers, even more preferably from 8 to 100 micrometers.
[0012] Preferably, the external surface 10 is delimited by a PVC layer.
[0013] Preferably, wherein the external surface 10 is delimited by an external layer obtained by rolling preceding hot stamping.
[0014] Preferably, the hot stamping temperature is in the range of 150 degrees Celsius to 250 degrees Celsius.
[0015] Preferably, the card is a chip card, such as a bank card. DESCRIPTION OF THE FIGURES
[0016] Other features, objectives and advantages of the invention will become apparent from the following description, which is purely illustrative and not limiting, and which should be read in conjunction with the accompanying drawings on which:
[0017] Fig. 1 is a top view of a map according to one embodiment, before application of a surface treatment to the map.
[0018] Fig. 2, Fig. 3 and Fig. 4 are three cross-sectional views of the card and a kit of surface treatment at different stages of implementation of a surface treatment process according to an embodiment.
[0019] Throughout the figures, similar elements bear identical references. DETAILED DESCRIPTION OF THE INVENTION
[0020] A map 1 has been represented on [Fig.1].
[0021] Card 1 has an external surface 10 and a second external surface 12 (visible on [Fig.2]) opposite the external surface 10.
[0022] The outer surface 10 and the second outer surface 12 are substantially flat. For example, these outer surfaces are formed as a result of a lamination step of the card 1, during which the card 1 is compressed in a direction normal to the outer surface 10 and the second outer surface 12.
[0023] The external surface 10 is typically rectangular, for example rectangular with rounded corners.
[0024] The card 1 has a thickness, which is measured in the direction normal to the external surface 10. The card 1 also has a length and a width, measured in the plane of the external surface 10. The length and the width are greater than the thickness.
[0025] Map 1 includes an outer layer delimiting the outer surface 10.
[0026] This outer layer can also delimit the second outer surface 12; in this case, the map 1 comprises only one layer. Alternatively, the map 1 comprises a stack of layers, the stack of layers comprising the outer layer 10 and at least one other layer delimiting the second outer surface 12. In this case, the outer layer delimiting the outer layer 10 does not delimit the second outer surface 12.
[0027] The outer layer has a glass transition temperature Tg. The outer layer is made of a material that softens when it reaches this glass transition temperature Tg.
[0028] In one embodiment, the outer layer is made of PVC, or polyvinyl chloride. Its glass transition temperature Tg is between 81°C and 98°C.
[0029] In certain embodiments (in particular that of [Fig. 1]), the card 1 comprises an electronic chip 14; the card 1 is then a smart card. The electronic chip 14 comprises electrical contacts flush with the external surface 10. The electrical contacts allow the electronic chip 14 to communicate with a card reader 1. The card 1 is, for example, a bank card, intended to authorize transactions.
[0030] The card 1 as shown in [Fig. 1] has not yet undergone any surface treatment. Before such surface treatment, the external surface 10 has a roughness, in particular an arithmetic mean roughness Ra. This roughness is substantially uniform.
[0031] The closer the roughness Ra is to zero, the smoother the external surface 10. When the roughness Ra is in a first range, the external surface 10 is said to be glossy. When the roughness Ra is in a second range higher than the first range, the external surface 10 is said to be satin-finished. When the roughness is in a third range, higher than the second range, the external surface 10 is said to be matte. The third range, for example, goes from 0.5 to 0.6.
[0032] It is desired to create variations in surface finish on the external surface 10, so as to create in the external surface 10 at least a first portion 10a with a roughness different from a second portion 10b. In [Fig. 1], the first portion 10a is a circular portion delimited by a dashed line, and the second portion 10b is a complementary portion, such that the external surface 10 consists of the first portion 10a and the second portion 10b. However, it is understood that this is only a non-limiting example: the first portion 10 may have other shapes, and it may be desirable to create more than two portions with different roughness in the external surface 10.
[0033] To create these variations in roughness, a surface treatment kit 2, schematically represented in [Fig. 2], is used. The surface treatment kit 2 comprises a stamping die 4, a film 6, and two rollers 8.
[0034] The stamping die 4 has a stamping surface 40 and heating means suitable for heating the stamping surface 40 to a target temperature called the "hot stamping temperature".
[0035] The stamping die 4 is known from the prior art. For example, the stamping die 4 comprises a head having a trapezoidal profile. The head has the stamping surface 40 and two inclined faces with respect to the stamping surface 40 and located on either side of the stamping surface 40. The stamping surface 40 forms the shorter base of the trapezoid, and the two inclined faces form two sides of the trapezoid.
[0036] Furthermore, the film 6 is made of a material having the property of being infusible at the aforementioned hot stamping temperature.
[0037] Film 6 is for example made of polyethylene terephthalate (PET).
[0038] Preferably, the polyethylene terephthalate is bi-oriented (BOPET). Using BOPET for the film 6 is advantageous because this material has very high crystallinity, which allows it to be very dimensionally and thermally stable. Since the amorphous portion of this material is small (because it is semi-crystalline), the glass transition temperature has little impact on its mechanical properties (it is around 80°C).
[0039] The film 6 has an upper surface and a lower surface opposite to the upper surface.
[0040] The film 6 has a thickness ranging from 8 to 200 micrometers, or even from 8 to 100 micrometers (this thickness is measured in a direction normal to the lower surface and the upper surface of the film 6).
[0041] The rollers 8 serve as a support for the film 6. For example, a first end portion of the film 6 is wound around one of the rollers 8, and a second end portion of the film 6, opposite to the first end portion, is wound around the other roller 8. The two rollers 8 are free to rotate about two parallel axes. In this way, it is possible to unwind the film 6 by rotating the two rollers 8 in two opposite directions of rotation, and conversely, to wind the film 6 by rotating the two rollers 8 in two opposite directions of rotation.
[0042] We will now describe a process for treating the external surface 10 of the card 1 using the surface treatment kit 2.
[0043] The outer surface 10 of the card 1 is placed opposite the lower surface of the film 6, and the stamping surface 40 is placed opposite the upper surface of the film 6. The film 6 is held by the two rollers 8. Typically, the roller axes are arranged horizontally, the card 1 is placed under the rollers 8, with the outer surface 10 oriented upwards and parallel to the roller axes.
[0044] Next, hot stamping of the card 1 is performed using the surface treatment kit 2, so as to vary the roughness of the external surface 10 in the first portion 10a thereof. Thus, a first portion 10a of the external surface 10 undergoes a change in roughness, while the second portion 10b does not undergo such a change in roughness.
[0045] Hot stamping is carried out without adding material to card 1. More specifically, hot stamping is carried out as follows.
[0046] The stamping die 4 is heated so that the stamping surface 40 reaches a desired hot stamping temperature. The hot stamping temperature is, for example, in the range of 150 degrees Celsius to 250 degrees Celsius.
[0047] The stamping die 4 is moved towards the card 1, so that the stamping die 4 presses the film 6 onto the card 1. More precisely, the stamping surface 40 moves in translation towards the card 1 in a direction normal to the outer surface 10. The stamping die 4 also moves in translation relative to the rollers 8. At a certain point, the stamping surface 40 comes into contact with the upper surface of the film 6 (see [Fig. 2]). The film 6 is then drawn in translation towards the card 1 by the stamping die 4. The rollers 8 rotate in the opposite direction to allow the film 6 to flex relative to the stamping surface 40 and unwind, without undergoing irreversible elongation. The stamping die 4 passes between the rollers 8. At a later stage, the lower surface of the film 6 comes into contact with the first portion 10a of the outer surface 10 of the card 1. The movement is then complete.
[0048] Ultimately, at this stage, the stamping surface 40 is in contact with the upper surface of the film 6, and the lower surface of the film 6 is simultaneously in contact with the first portion 10a of the outer surface 10 of the card 1 (see [Fig. 3]). Conversely, the film 6 is at a distance from the second portion 10b of the outer surface 10 of the card 1.
[0049] Heat transfer then occurs from the hot stamping die 4 to the board 1, via the film 6. As previously noted, the film 6 is made of a material that is infusible at the hot stamping temperature. Consequently, the heat transfer does not melt the film 6.
[0050] Heat transfer to the card 1 through the film 6 causes softening of the card 1 at the first portion 10a of the external surface 10. The first portion 10a of the card 1 is softened at the glass transition temperature Tg, which is lower than the hot stamping temperature. The hot stamping temperature and the material of the film 6 are chosen jointly for this purpose. This softening causes a change in the roughness of the first portion 10a. In contrast, the condition of the second portion 10b of the external surface 10 remains unchanged, being at a distance from the film 6.
[0051] The external surface 10 of the card 1 now has a roughness Ra' in the first portion 10a, and the initial roughness Ra in the second portion 10b, Ra and Ra' being different. The first portion 10a is typically made brighter than the second portion (Ra' <Ra).
[0052] The pressure exerted on the card 1 by the film 6 varies according to the fineness and rendering of the marking sought.
[0053] Next, the film 6 and the stamping matrix 4 and the film 6 are moved away from the card 1 (see [Fig.4]).
[0054] As previously stated, the first portion 10a in which a variation in roughness has taken place can have various shapes.
[0055] In some embodiments, the processing kit includes a relief pattern which is imprinted in the first portion 10a of the surface during hot stamping.
[0056] In some embodiments, the embossed pattern is formed by the stamping die 4. This embossed pattern is then delimited by the stamping surface 40. During the process, the film 6 adapts to the embossed pattern, and it is through the film 6 that the pattern is printed on the card 1.
[0057] In other embodiments, the relief pattern is formed by the film 6. This relative pattern is then delimited by the lower surface of the film 6. The stamping surface 40 can then be flat, and simply push the pattern of the film 6 towards the card 1.
[0058] The choice of PVC for the external surface 10 of the card 1 to be treated is advantageous because this material is very malleable above its glass transition temperature Tg.
[0059] The hot stamping described above can be carried out in several portions of the external surface 10 of the card 1.
[0060] The process described above has the advantage of not requiring any consumables such as varnish, which would increase the manufacturing cost of the card 1. Furthermore, the equipment required to implement the process (the treatment kit 2) remains relatively inexpensive. The inventors noted that the process is quick to execute and allows for the definition of areas of varying roughness with great precision.
Claims
Demands
1. A method for treating an external surface (10) of a card (1), the external surface (10) comprising a first portion (10a) and a second portion (10b), the method comprising hot stamping the first portion so as to vary the roughness of the first portion (10a) relative to the roughness of the second portion (10b), the hot stamping being carried out without adding any material to the card (1), wherein the hot stamping comprises applying a film (6) to the first portion (10a) but not to the second portion (10b) using a stamping die (4), wherein: • the stamping die (4) is heated to a hot stamping temperature, • the film (6) is infusible at the hot stamping temperature, • the hot stamping temperature and the film (6) are adapted to cause a softening of the first portion (10a).
2. A method according to the preceding claim, wherein the film (6) comprises a raised pattern which is imprinted in the first portion of the surface during hot stamping.
3. A method according to any one of the preceding claims, wherein the stamping die (4) comprises a relief pattern which is imprinted in the first portion of the surface during hot stamping.
4. A method according to any one of the preceding claims, wherein the film (6) is made of polyethylene terephthalate (PET).
5. A method according to the preceding claim, wherein polyethylene terephthalate is bi-oriented (BOPET).
6. A method according to any one of the preceding claims, wherein the film (6) has a thickness of 8 to 200 micrometers, preferably 8 to 100 micrometers.
7. Method according to any one of the preceding claims, the external surface (10) is delimited by a PVC layer.
8. A method according to any one of the preceding claims, wherein the external surface (10) is delimited by an external layer obtained by rolling prior to hot stamping.
9. Method according to any one of the preceding claims, in which the hot stamping temperature is in the range of 150 degrees Celsius to 250 degrees Celsius.
10. A method according to any one of the preceding claims, wherein the card (1) is a smart card, such as a bank card.