FR2696650A1 - Procedure for decorating upper surface of ski which has two different-coloured coating layers - abrading portions of upper layer by sand-blasting to expose under layer and then varnishing - Google Patents

Abstract

The procedure consists of projecting a jet of a pulsed fluid charged with abrasive particles against the upper surface of the ski to remove parts of the upper layer and expose the under layer. The abrasive particles can be of white corundum, measuring between 20 and 200 micrometres in size, projected by a pulsed air flow at a pressure of 1-4 bars. After the localised removal of the upper coating layer, the upper surface of the ski, including the abraded portions, can be given a coating of a protective varnish with a transparent matt, satin or gloss finish. ADVANTAGE - Produces decorative effect with greater reliability and more economically.

Description

PROCESS FOR DECORATING A SKI.

 The invention relates to a method for decorating a ski; it relates more particularly to a method for obtaining on a ski gradient effects; it also relates to skis decorated in this way.

 It is well known to decorate skis, in particular their upper face with all appropriate colored patterns. Once the decoration has been affixed by all known techniques, such as transfer, screen printing, pad printing, the decoration is then covered with a transparent layer of varnish which is deposited in one or more thicknesses by spraying, watering (curtain), etc. .., then cross-link. Depending on the desired effect, the transparent varnish is matt or glossy.

 These techniques are however expensive, random or difficult to implement, when looking for gradient effects, in particular gradient effects of different colors.

 The invention overcomes these drawbacks. It aims at a process which makes it possible to obtain in a reliable, economical and aesthetic manner effects of degradations on surfaces of decorated skis.

 This process for decorating a ski whose upper surface comprises at least two superimposed layers colored differently, respectively a lower layer and an upper layer, is characterized in that it consists in projecting on part of this surface a jet of pulsed fluid, charged of abrasive particles, until at least removing the upper layer to make the lower layer appear locally.

 In other words, the invention consists, after having covered the surface of the ski with at least two superimposed layers colored differently, by sandblasting the upper layer to make it disappear, at least on predetermined preferential surfaces.

 In a variant of the invention, a step is taken after this step of coating said surface with a layer of transparent, matt, satin or glossy protective varnish.

 In a variant of the invention, this coating phase is carried out prior to the abrasion operation, also called sanding, when the abrasive particles consist of sand or a neighboring material.

 As is known, sandblasting is an operation which consists of using a jet of pulsed fluid, in particular air, to spray abrasive particles which pickle the areas to be treated on the surface. Thus, sandblasting, a known technique, used for a very long time in industry as a stage of surface preparation prior to the application of a coating, makes it possible, in this case, to reveal lower layers and to vary the decorations from a selection of overlapping layers.

In addition, in the present case, as the particles of particles are a little dispersed at the outlet of the nozzle, the connection between the two superimposed layers is not clear or abrupt, but on the contrary slightly progressive or decreasing, which gives a very good degraded effect much sought after.

 Advantageously, in practice, the sandblasting is carried out continuously with air under a pressure of between 1 and 4 bars (10 5 and 4.10 5 Pascals); indeed, it has been observed that if the pressure is less than 1 bar, the aggression is too low, even insignificant; similarly, if this pressure is greater than 4 bars, the attack on the lacquer layer becomes too brutal and risks causing total degradation of the support.

 As particles, particles of white corrindon, with a particle size of between 20 and 200 micrometers, are advantageously used.

 The manner in which the invention can be implemented and the advantages which ensue therefrom will emerge more clearly from the example of embodiment which follows, given by way of nonlimiting indication in support of the appended figures.

 Figure I is a schematic representation of the top of a ski in decoration phase according to the invention.

 FIG. 2 is a representation of a section produced along line A-A of FIG. 1.

 Figure 3 is a schematic view of a partial section of an effect obtained by the method of the invention.

 Figure 4 is a view similar to that of Figure 3 of another type of effect obtained by the method of the invention.

 According to the invention, the ski (1) to be decorated is kept on a work table (not shown). A stencil is then positioned on the ski constituted by protectors (2) surrounding a plate (4), within which particular patterns (5), intended to be revealed on the upper face of the ski, are cut out. A nozzle (3), intended to pulsate an air jet comprising abrasive particles, is mounted on a gantry (not shown) capable of moving along the axis (6), said nozzle being caused to move along the line AB within said portal.

 Advantageously, and as shown in FIG. 2, the possible path of the nozzle (3) in the main direction of the ski is offset (6), so as to allow obtaining a gradient effect at level of the upper surface of the ski. Thus, the nozzle is offset with respect to the patterns (5) of the stencil, and the more the number of abrasive particles reaching said patterns decreases, and moreover, the lower the speed of these particles, and therefore their abrasive power.

 The ski according to the invention comprises a basic structure (9) obtained by any known method, such as for example by injection. This ski has on its upper surface two superimposed layers of lacquer, respectively a first layer (10) of a defined color, and a second layer (11) of another color.

 The conditions of abrasion and in particular of sanding make it possible first of all to strip the upper layer (11), then to mattify the lower layer (10), without stripping this last layer over its entire thickness.

In this way, a cavity (12) is created, allowing the second color to appear.

 Advantageously, at the end of this sandblasting step, the upper face is coated with a uniform layer of varnish, also filling the cavities (12). This varnish is crosslinked, in order to give it in known manner its resistance properties.

 As varnish, products in common use are used for this application, such as Ut varnishes, one or two-component polyurethane varnishes. In practice, layers of 70 to 150 g / m2 are deposited, for thicknesses of 70 to 150 micrometers.

 Unexpectedly, it was observed that the sanding operation on the lacquer layer at the spatula considerably reduced the well-known risks of cracking. This result is of great interest, because this aspect problem arises relatively frequently. It is thus observed that the sanding of the lacquer causes a surface hardening which mitigates the risks of subsequent cracking.

 In another embodiment of the invention, the cavities (12) generated by sanding are filled with a crosslinkable colored material, such as in particular a lacquer or a chromed or golden ink, the adhesion of which is made possible at said cavity due to the previous sanding operation. As this sanding operation can be carried out after the coating of the varnish layer, a finished ski is obtained without any other additional step. This additional lacquer layer is generally crosslinked, so that it gives the area under consideration a hollow appearance (14) recessed with respect to the upper layer of varnish.

 In another application of the invention, said cavities (12) are filled with polyurethane of transparent aliphatic casting, giving a magnifying effect to the dome (13) thus produced, thus revealing the lower color (10). Again, this additional addition adheres to said cavity due to the previous sanding operation.

 The invention thus makes it possible to obtain decor effects, in particular of gradient increasingly sought after on skiing.

Claims (8)

 1 / Method for decorating a ski, the upper surface of which comprises at least two layers (10, 11) superimposed differently colored, respectively a lower layer (10) and an upper layer (11), characterized in that it consists in projecting on a part of this surface a jet of pulsed fluid, charged with abrasive particles, until removing the upper layer (11) in order to locally reveal the lower layer (10).  2 / A method according to claim 1, characterized in that after the local abrasion operation of the upper layer (it), the upper surface of the ski, including the abraded areas is coated with a layer of protective varnish transparent mat, satin or gloss.  3 / Method according to one of claims I, characterized in that prior to the local abrasion operation of the upper layer (it), the upper surface of the ski is coated with a layer of matt transparent protective varnish , satin or shiny.  4 / A method according to claim 1, characterized in that the projection is a sandblasting whose fluid consists of air at a pressure of 1 to 4 bars (10 5 to 4.10 5 Pascals), and whose abrasive particles are consisting of grains of white corrindon with a particle size between 20 and 200 micrometers.  5 / Method according to one of claims 1 to 2, characterized in that prior to sandblasting:  - Provisionally mask preferential areas which it is desired to retain the color of the upper layer (11);  - then the charged pulsed jet is projected to affect only the upper layer (11) not masked,  - And finally, we remove the temporary masks protecting the areas of the upper layer that we want to keep.  6 / A method according to claim 5, characterized in that the unmasked areas are abraded until defining cavities (12), the depth of which reaches without exceeding the lower layer (10).  7 / A method according to claim 6, characterized in that said cavities (12) are filled with a crosslinkable colored material, and in particular by a lacquer or an ink, optionally loaded with metallic particles, adhering to the internal walls of said cavities.  8 / A method according to claim 6, characterized in that said cavities (12) are filled with a transparent crosslinkable material, and in particular by a varnish or a polyurethane, adhering to the internal walls of said cavities (12).