FR2730189A1 - Method of formation of colour motif on thermoplastic support - Google Patents

Abstract

The method of forming a colour motif on a thermoplastic support commences with deposition of a layer (2) of paint or ink to act as a top coat on the support. The top coat is then partly removed by exposure to a light beam to leave the desired pattern. A screen layer (4) is deposited between the top coat and the surface that is to be revealed by removal of the top coat. The screen layer has a higher absorption rate of luminous energy than does the layer to be revealed. The screen layer can be formed by paint or by ink, and has a thickness of between 5 and 20 micron. The layer to be exposed is formed by a sub-layer of paint or ink, which is deposited directly on the plastic support.

Description

 The subject of the present invention is a method of forming at least one color pattern on a support made of thermoplastic material, for example for vehicle dashboards, car radio facades, signs or for any other element of a device.

 Processes are known for forming on a support, in particular a thermoplastic material, at least one pattern which consists in depositing on the support a layer of paint or finishing ink and removing along a contour corresponding to the pattern to be discovered, the finishing layer by means of a beam of light energy to reveal said pattern.

 The pattern to be discovered can be formed either by the upper face of the support made of thermoplastic material, or by a layer of paint or ink interposed between the support and the finishing layer.

 However, this type of process poses problems.

 Indeed, each material has a different absorption power of light energy which is a function of its color, its clarity and its saturation.

 Thus, light colors absorb less light energy emitted by a beam of light energy than dark colors.

 Consequently, during the formation of a pattern by means of a beam of light energy on a support of thermoplastic material covered with a finishing layer, in particular of a light color, it is necessary to increase the sublimation energy. of the top coat to locally destroy this layer and reveal the desired pattern.

 However, this increase in the sublimation energy has the disadvantage of degrading, before the sublimation of the finishing layer, the support or the layer of paint or ink on which the pattern is formed, because this support or this layer absorbs usually more energy from the electron beam than the topcoat.

 The object of the invention is to propose a method for forming at least one color pattern on a support made of thermoplastic material which avoids the drawbacks mentioned above.

 To this end, the subject of the invention is a process for forming at least one color pattern on a support made of thermoplastic material, in which a layer of colored paint or finishing ink is deposited on the support and removes, according to an outline corresponding to the pattern, the finishing layer by means of a beam of light energy to reveal a layer to be discovered, characterized in that one deposits, between the finish layer and the layer to be discovered of the pattern, a screen layer whose absorbing power of light energy is greater than the absorbing power of light energy of the layer to be discovered of the pattern.

According to other features of the invention
- the screen layer is a layer of paint or a layer of ink,
- the screen layer has a thickness of between 5 and 20 microns,
the layer to be discovered of the pattern is formed by the upper face of the support of thermoplastic material,
- The pattern to be discovered layer is formed by an under layer of paint or ink deposited on the upper face of the support below the screen layer.

Other characteristics and advantages of the invention will appear during the description which follows, given by way of example and made with reference to the accompanying drawings, in which
- Fig. 1 is a view in cross section and on an enlarged scale of a first embodiment of a support comprising a pattern obtained by the method according to the invention,
- Fig. 2 is a cross-sectional view on an enlarged scale of a second embodiment of a support comprising a pattern obtained by the method according to the invention.

 In Fig. 1, there is shown a support 1 of thermoplastic material usable for forming patterns on a dashboard of motor vehicles, a facade of car radios, a sign or any other element of an appliance.

 On the support 1 is deposited a finishing layer 2 such as for example a layer of paint or ink. This finishing layer 2 is deposited by spraying, pad printing or screen printing and the color of said layer 2 is for example clear such as red, white, blue or light green or yellow.

 To trace a pattern 3 on the support 1, the finishing layer 2 is removed by applying on this layer 2 a beam of light energy which has the effect of locally sublimating said layer 2 and making the upper surface appear of the support 1 according to the desired pattern and which constitutes the layer to be discovered.

 In this case, the color of the support 1 corresponds to the color of the pattern to be displayed.

 However, during the application of the light energy beam on the finishing layer 2, there is a risk of deterioration of the layer to be discovered which, in the embodiment shown in FIG. 1 is formed by the upper face 1a of the support 1.

 In fact, during marking, the sublimation energy of the finishing layer which is proportional to the absorption power of the light energy is too high.

 Consequently, the upper face 1a of the support 1 absorbs more light energy from the beam than the finishing layer 2, which causes the sublimation of said upper face 1a before the sublimation of the finishing layer 2, thus causing degradation of the layer. to discover.

 To avoid degradation of the layer to be discovered, the method according to the invention consists in depositing between the finishing layer 2 and the layer to be discovered formed by the support 1, a screen layer 4 whose absorbing power of light energy is greater than the absorption power of the light energy of the layer to be discovered of the pattern 3.

 As a result, the intermediate screen layer 4 collects the excess energy to sublimate the finishing layer 2.

 The screen layer 4 is formed by a layer of paint or a layer of ink deposited by pad printing or screen printing.

 Preferably, the screen layer 4 absorbs light energy better than the finishing layer 2 and has a thickness of between 5 and 20 microns.

 According to a variant shown in FIG. 2, the layer to be discovered of the pattern 3 is formed by an undercoat 5 of paint or ink and of color corresponding to the color of the pattern 3 to appear and deposited on the upper face of the support 1 below the layer screen 4.

 The screen layer 4 absorbing more energy from the light energy beam than the finishing layer 2 makes it possible to locally destroy and according to the pattern to cause said finishing layer to appear, without damaging the layer to be discovered formed either by the support of thermoplastic material, either by an undercoat of paint or ink.

 In addition, the screen layer acts as an anti-migration layer of colors between the finish layer and the support or the undercoat of paint or ink.

Claims (6)

 1. Method for forming at least one pattern  (3) in color on a support (1) in thermoplastic material  tick, in which is deposited on the support (1) a  layer (2) of paint or color finishing ink  and we remove, according to a contour corresponding to the pattern  (3), the finishing layer (2) by means of a beam  of light energy to make a layer appear  discover, characterized in that one deposits, between the  finishing layer (2) and the layer to be discovered of the pattern  (3), a screen layer (4) whose absorption power  light energy is greater than the absorbing power  tion of the light energy of the layer to be discovered  pattern (3).  2. Method according to claim 1, character  laughed in that the screen layer (4) is a layer of --painting.  3. Method according to claim 1, character  laughed in that the screen layer (4) is a layer  ink.  4. Method according to any one of  Claims 1 to 3, characterized in that the layer  screen (4) has a thickness of between 5 and 20 microns.  5. Method according to claim 1, character  laughed at in that the layer to be discovered of the pattern (3) is  formed by the upper face (la) of the support (1) in  thermoplastic material.  6. Method according to claim 1, character  laughed at in that the layer to be discovered of the pattern (3) is  formed by an undercoat (5) of paint or ink  deposited on the upper face (la) of the support (1) at  below the screen layer (4).