EP0606556A1 - Decoration procedure of the upper ski - Google Patents

Abstract

The invention relates to a method for decorating the upper surface (topsheet) of a ski, comprising a stage of assembling and securing a thick outer layer (1) made from transparent plastic material on an opaque inner layer (2). Prior to the assembly stage, a first decoration is transferred onto the outer face (10) of the outer layer (1) and a second, inner decoration different from the first decoration is transferred onto one of the faces (11, 20) of the inner layer which contact the outer layer (1). The invention makes it possible economically to produce varied and easily interchangeable decorations. <IMAGE>

Description

Method of decorating a ski top.

The present invention relates to a method of decorating a ski top. The terminology "ski" must be understood in the broad sense and includes alpine skiing, cross-country skiing, monoski and snowboarding.

The upper surface of a ski is required to have a certain number of characteristics; various markings and aesthetic patterns, the trade mark, the identification of the ski model, indications relating to the size or mounting of the bindings and others. Increasingly numerous, these distinctive signs and aesthetic elements must easily differentiate from each other. The enrichment of the decor by creating attractive and new effects is an increasingly important concern of equipment manufacturers. Of course, it is also necessary to take into account the constraints of use of the skis and in particular the constraints of resistance of the surface and the decorations to mechanical aggressions (strokes of the stick, ...) and physicochemicals (temperature, UV, solvents, humidity).

In addition, the interchangeability of the decorations must be able to be done quickly and economically from one model to another and from one year to another. Thus, the models of the same range often have common patterns or markings and other distinctive ones. Due to the increase in the number of models from all manufacturers, the management of decoration and markings is becoming increasingly cumbersome, complex and expensive.

Among the known methods, the decoration or marking is carried out on the upper surface of the ski, generally made of plastic by printing means such as screen printing, sublimation, hot marking or pad printing.

Japanese document n ° 61-154586 describes a process for decorating a ski by screen printing, the object of which is to print letters or patterns using an ink of high surface tension in order to obtain protruding drawings or letters on ski. A disadvantage of this type of decoration is that it does not withstand aggression well and the aesthetic effect is only short-lived.

The document of the applicant FR 2 620 975 describes a decoration process by sublimation which consists in transferring sublimable inks from a decoration pattern onto the external face of an opaque monolayer sheet of contrast; then to assemble by hot gluing the monolayer sheet with the rest of the ski.

Document FR 2 387 793 describes a sublimation process by transfer of sublimable dye in a transparent layer secured to a layer of binder containing a pigment.

The document PR 2 620 974 relates to a decoration process which consists in using a two-layer sheet; one of the layers being transparent, the other layer being opaque. The transfer is carried out by sublimation on the outer face of the opaque layer, then the bi-layer thus predecorated is assembled with the ski by application on the side of the opaque outer face on the upper face of the ski body.

The document FR 2 580 943 consists in marking a shaped ski. For this, the marking is carried out on a flat sheet of translucent material. The sheet is shaped and then attached to the surface of the ski so that the marking is on the face of the sheet in contact with the upper surface of the ski. The marking is thus protected against external aggressions.

Document FR 2 596 286 relates to a protective element of a ski comprising two layers assembled together of different chemical nature. The opaque inner layer is flexible and suitable for bonding, while the transparent outer layer is rigid. The decoration can be printed by sublimation or by screen printing on the underside of the flexible layer.

Document FR 2 421 071 relates to a process for producing upper ski faces which consists in printing a decoration on a paper by screen printing, in covering the upper face of the decorated paper with transparent paper and its lower face with one or more papers. stacked supports. Then, the multi-layer assembly is thus impregnated in a synthetic bath. Finally, said assembly is treated with a press at high temperature and the assembly is cut to paste it on the upper face of the ski.

The current state of decoration processes limits the possibilities of obtaining durable, sufficiently rich and differentiated decors, easily interchangeable while remaining economical.

The object of the present invention is therefore to provide a method of decorating a ski top having the advantages set out above.

One of the aims of the invention is also to be able to easily and economically produce varied and interchangeable decorations. In particular, decoration can be carried out for a full range of skis made up of models with sufficiently decorative patterns different and distinctive, without having to be obliged to design a complete decoration for each model.

Another object of the invention is to be able to produce new decorative and aesthetic effects on a ski, such as effects of depth, of relief or of effects variable according to the angle of observation from above.

Another object of the invention is to be able to produce a durable decoration against external aggressions and under all conditions of use.

For this, the invention relates to a method of decorating a ski top comprising a step of assembling and joining a thick outer layer of transparent plastic on an opaque inner layer. Prior to the assembly step, a first decoration is transferred to the external face of the external layer and a second internal decoration different from the first decoration on one of the faces in contact of the internal layer with the layer external.

The thickness of the transparent layer is greater than 0.5 mm, preferably between 0.5 mm and 1.1 mm.

The first and / or the second decoration is (are) applied according to a sublimation printing method, serigraphy, pad printing, hot stamping.

In a first embodiment, the second decoration is applied to the internal surface of the transparent external layer.

We have on each surface of the transparent layer a support paper which carries sublimable dyes, we proceed to the hot transfer, inks of each paper simultaneously inside the transparent layer whose thickness must be greater than the total depth penetration of the inks, the outer layer thus printed is assembled and then secured to the opaque layer.

The transparent outer layer and the opaque inner layer are chosen in materials having close or close melting temperatures and the layers are joined together by welding.

The transparent outer layer is ABS or AS mixed with TPU (thermoplastic polyurethane elastomer) and the opaque inner layer is ABS or AS mixed with pure TPU or ABS or AS.

In a second embodiment, the second decoration is applied to the surface of the opaque internal layer intended to come into contact with the internal surface of the transparent layer during the assembly and joining, there is on one side of the transparent outer layer a support paper which carries sublimable inks, there is on the other surface of said layer a solid film of hot-melt adhesive having good adhesion properties with the inner and outer layer, the ink is transferred simultaneously and the film is bonded to the transparent outer layer while hot, then the transparent outer layer is assembled on the opaque inner layer by applying the film side glue on the decorated side of the opaque inner layer and it is heated to obtain adhesion, the transparent outer layer is chosen from aliphatic polyamides having good UV resistance and capable of sublimation, preferably polyamides 11 or 12 , the inner opaque layer is chosen from aliphatic polyamides, copolymers based on polyamide (s) such as polyesteramides, polyetharamides, com positions of copolymers based on polyamide and modified polyolefin (s), copolymers of styrene and of carboxylic acid or its anhydrous.

The bonding film is based on polymers or copolymers of polyethylene or EVA grafted by the action of carboxylic acid, anhydrous carboxylic acid or ester of carboxylic acid.

Other characteristics and advantages of the invention will emerge from the description which follows with reference to the appended drawings which are given only by way of nonlimiting examples.

Figures 1 to 5 illustrate a first embodiment of the decoration of a ski top according to the method.

Figures 6 to 10 illustrate a second particular mode of the process.

Figures 11 and 12 illustrate a non-limiting example of the conformation of a decorated top according to the method of the invention and its simultaneous adhesion with an upper reinforcing element.

The method according to the invention firstly requires the use of a monolayer plastic sheet (1) made of transparent or translucent material, this sheet which will be called "transparent layer" in the description below. On each face (10, 11) of the layer (1), a decoration is printed by transfer of sublimable dyes. The decoration pattern to be printed is in a manner known per se contained on a sheet of support paper (40, 41) which is applied under a pressure (P) at a temperature (T) for a time (t) against each of the faces ( 10, 11). Preferably, the transfer takes place simultaneously on both sides. According to a characteristic of the invention, the conditions for the sublimation reaction have been determined so that, taking into account the thickness (e) of the transparent layer (1), the migration front (50, 51) of the sublimed dyes of each decoration does not not meet. In other words, the sum of the depths (p1) and (p2) of penetration of the inks is less than the thickness e of the transparent layer.

In the particular case of the example described, the transparent layer consists of an ABS (Acrylonitrile, Butadiene, Styrene) or AS (Acrylonitrile, Styrene) transparent in a proportion of 70 to 95% mixed with a TPU (Thermoplastic polyurethane elastomer) hardness between 95 shA and 80shA in proportion of 30 to 5%; the first proportion, however, tends to give tints that turn yellow over time. On the other hand, any proportion gives excellent resistance to cracking at very low temperatures. Such a sheet has the advantage of being able to be easily shaped after decoration on a non-flat ski structure.

The thickness of the layer is greater than 0.5 mm, preferably between 0.5 mm and 1.1 mm. Sublimation is carried out at a temperature of 160 ° C., a pressure of 1 bar for approximately 3 minutes 30 seconds. The limit depth of each front is of the order of or slightly greater than 100 µm. The patterns of each decoration are of course different and can only partially cover the surface of each face (10, 11) of the layer.

According to Figure 3, the next step is to assemble the layer thus pre-decorated on a second layer or sheet (2) of opaque material. In the specific example described; the material is identical to that of the transparent layer (1) or is pure ABS. The important thing is that the two layers (1, 2) have close or close melting temperatures in order to be able to be joined together by heat sealing (FIG. 4).

The second layer (2) is made opaque by pigmentation, preferably in white, for example by means of titanium dioxide incorporated in the manufacture. Relative to the pigmentation of the contrast layer which is intended to reveal the two superimposed decors, it should be noted that we are by no means limited to the white color. Let us quote for example the whole range of clear, metallic or pearly shades.

According to a variant of Figures 1 and 2; one can foresee that after decoration of the transparent layer (1), one simply applies a layer of lacquer on the internal surface (11) of the layer to reveal the decor. In this case, the lacquer replaces the opaque layer (2).

The sublimation technique is given as a preferred mode of the invention because it allows very rich and above all durable decors to be produced. They are particularly resistant to abrasion due to the ink gradient created in depth. If the thickness of the transparent layer is sufficient, it is possible to obtain very marked relief effects allowing for example to keep a common background pattern and to interchange a surface pattern to obtain a differentiation of the models of the skis of the same range.

However, the invention extends to other techniques or methods of ink transfer. We can cite as an example; serigraphy, pad printing or hot stamping. Thus one or the other of the techniques can be used for the decoration of each face (10, 11) of the transparent sheet (1).

The use of the materials of each layer (1, 2) is not also limited. All materials that can be heat sealed easily, suitable for decoration and sufficiently resistant to the constraints imposed by the practice of skiing. The outer layer must also be sufficiently transparent. Thus, it is possible to add plastic materials such as polycarbonates, polyamides and derivatives, sulfonated polyesters, polyesters, transparent polyolefins such as low density polyethylenes and polypropylenes, plasticized PVCs (polyvinyl chloride).

It should be noted, however, that on certain plastics such as polycarbonates, traditional markings are difficult to achieve.

The decorative bilayer thus formed is then assembled to the remaining structure (3) of the ski as illustrated in FIG. 5. Thus, the interlocking of the opaque internal layer (2) can be carried out by any means known to those skilled in the art. the art, for example either with an adhesive comprising organic solvents, or with thermosetting adhesives (epoxy, polyester or phenolic) or else hot-melt adhesives in the form of solid and manipulable films, for example.

The assembly or bonding phase can be integrated into a more complex process involved in the manufacture of modern skis. Figures 11 and 12 which are an example will describe it more precisely below.

As shown in Figure 5, the transparent layer (1) constitutes the outer layer of the ski. It comprises patterns (100, 101, 102) in the foreground which have been transferred to the external surface (10) and patterns (110, 111) in the background, different from the patterns (100, 101, 102) which have been transferred to the internal surface (11). The relief effect can be more or less marked depending on the thickness of the layer, the penetration depth of the inks, the nature of the material which diffuses more or less the inks giving a more or less significant contrast.

Another mode, illustrated in FIGS. 6 to 10, of the method according to the invention can be envisaged when it is desired to use materials of different nature for each layer (1, 2). In this case, a decoration is transferred to one of the faces (10) only of the transparent layer (1). For this, the sheet of decorative paper (40) retaining the sublimable inks is applied to the face (10). Simultaneously, a transparent bonding film (4) is applied to the other face (11). This film is solid and therefore easy to handle at room temperature. It is a film known as "compatibilizing", that is to say it is chosen so as to have good adhesion properties, both with the material of the layer (1) and with the material of the opaque layer on which the transparent layer (1) is intended to come into contact. The film can be either monolayer or bilayer. It has a very small thickness of the order of a few microns.

In the particular case of the example described, the choice of the applicant is the use of a transparent layer (intended to form the layer exposed to weathering and mechanical stresses) in aliphatic polyamide, preferably in PA11 or 12. These materials have the properties of being transparent, UV resistant, hot creep, cold cracking. They are also easily sublimable.

The thickness (e) of the layer must be chosen so as to be greater than the depth (p) of penetration of the inks.

The sublimation conditions are chosen so that the inks are transferred to the layer and the adhesive film is adhered to simultaneously. Thus, with the materials chosen, the temperature is 180 ° C. at a pressure of 2 bar for approximately 2 minutes and 30 seconds.

At the same time (FIG. 8), the method requires the use of a second opaque layer (2), on one (20) of the faces of which, a second decoration is transferred. We operate as before by applying to said face (20) a paper (41) containing the sublimable inks, it is heated while maintaining a certain pressure for a certain time. In the case described, the layer consists of a material whose composition is a copolymer of styrene and maleic anhydride (SMA). This material is particularly suitable for decoration by sublimable ink transfer.

By the use of this material, the migration of the inks takes place in a moderate and not very diffuse way creating an interesting clarity of the pattern. The color rendering and tone are excellent.

As illustrated in Figures 9 and 10, the next step is to assemble the two layers (1, 2) together. For this, the face (11) of the transparent layer (1) comprising the bonding film is applied to the face (20) which has been predecorated with the opaque layer (2). The adhesion of the film on the opaque layer (2) is obtained by heating. Thus, a pressure of the order of 8 bar is applied, at a temperature of 130 ° C. for 5 min. The choice of material for the opaque layer is important because it must withstand the conditions of adhesion to degradation of the sublimated decoration in the opaque layer. Indeed, the fact of carrying out a second heating cycle under pressure tends to cause a resumption of the diffusion of the inks inside the opaque layer. The inks affected by the phenomenon, which by their relative position defined a precise decoration pattern, will therefore diffuse in the material in a completely anarchic way; which in the context of the method according to the invention, would seriously harm the quality of the decoration pattern of the opaque inner layer.

By way of nonlimiting example, the opaque internal layer (2) can be chosen from aliphatic polyamides, copolymers based on polyamide (s) such as polyesteramides or polyether-amides, copolymer compositions (s) based polyamide (s) and modified polyolefin (s), copolymers of styrene and acid, anhydrous or carboxylic ester, preferably maleic or anhydrous.

The bonding films are based on polymers or copolymers of polyethylene or EVA grafted by the action of anhydrous acid, or of carboxylic ester.

As in the previous case, the decoration subassembly thus obtained is then assembled with the rest of the elements of the ski within the framework of the manufacturing process proper.

The adhesion of the film (4) on the opaque layer (2) of SMA is obtained by heating during a second assembly step illustrated in FIGS. 6 and 7.

Figures 11 and 12 illustrate an example of assembly and forming of the decorative bilayer comprising the transparent outer layer (1) predecorated and the opaque inner layer (2), with the upper reinforcement element (5) of the ski.

In a hot forming mold comprising a lower die (7), there is a stack of layers intended to form the top of the ski; the bilayer (1, 2) of decoration pre-decorated according to the invention, a layer (5) intended to form the upper reinforcement of the ski and a solid film (6) compatibilizing intended to ensure the bonding of the top with the rest of the ski.

The reinforcing layer (5) consists of one or more reinforcing textile plies impregnated with a thermosetting or thermoplastic resin. In the case of a reinforcement (5) of a textile sheet preimpregnated with a thermosetting resin, the hot pressing operation ensures the crosslinking or the additional crosslinking of the resin and the adhesion of the film (6) to the reinforcement (5). After hardening, the top thus formed can be removed.

The subsequent manufacturing operation consists in placing the top as well as the lower elements (edges, sole, lower reinforcement, etc.) in a mold, then injecting foam between these elements to form the core of the ski.

The manufacturing process is described more precisely in patent application No. 2,654,644 belonging to the applicant. It is of course only a non-limiting example and is given only to illustrate the integration of the invention in the more general context of ski manufacturing.

As a variant (not shown); provision may be made for the transparent layer (1) and the opaque layer (2) to be assembled together during the actual forming step on the top of the ski or integrated in a molding step for the ski.

Claims (12)

Method of decorating a ski top comprising a step of assembling and securing a thick outer layer (1) of transparent plastic on an opaque inner layer (2),
characterized in that, prior to the assembly step, a first decoration is transferred to the external face (10) of the external layer (1) and a second internal decoration different from the first decoration on one of the faces in contact (11, 20) of the inner layer (2) with the outer layer (1). Decoration method according to claim 1, characterized in that the thickness of the transparent layer (1) is greater than 0.5 mm, preferably between 0.5 mm and 1.1 mm. Method according to claim 1 or 2, characterized in that the first and / or second decoration (s) is (are) applied according to a method of sublimation printing, screen printing, pad printing, hot stamping. A method of decorating a ski top according to claim 1, 2 or 3, characterized in that the second decoration is applied to the opaque inner surface (11) of the transparent outer layer (1). Decoration process according to claim 4, characterized in that: - there is on each surface (10, 11) of the transparent layer (1) a support paper (40, 41) which carries sublimable dyes, - the hot transfer is carried out simultaneously, inks of each paper (40, 41) inside the transparent layer (1) whose thickness (e) must be greater than the total depth (p1, p2) of ink penetration, - The outer layer (1) thus printed is assembled and then secured to the opaque layer (2). Method according to claim 5, characterized in that the transparent outer layer (1) and the opaque inner layer (2) are chosen in materials having near or close melting temperatures and in that the bonding is carried out layers (1, 2) together by welding. Method according to claim 6, characterized in that the transparent outer layer (1) is an ABS or AS mixed with a TPU (thermoplastic polyurethane elastomer), and in that the layer opaque internal (2) is ABS or AS mixed with TPU or pure ABS or AS. Method according to claim 1, 2 or 3, characterized in that the second decoration is applied to the surface (20) of the opaque internal layer (2) intended to come into contact with the internal surface (11) of the layer transparent (1) during the assembly and joining step. Method according to claim 8, characterized in that: - one has on one side (10) of the transparent outer layer a backing paper (40) which carries sublimable inks, - there is on the other face (11) of said layer (1) a solid film of hot-melt adhesive (4) having good adhesion properties with the internal (2) and external (1) layer, the transfer of the inks and the bonding of the film (4) to the transparent outer layer (1) are simultaneously carried out hot - the transparent outer layer (1) is then assembled on the opaque inner layer (2) by applying the face (11) on the adhesive film side (4) to the decorated face (20) of the opaque inner layer (2) and heated to obtain adhesion. Method according to claim 9, characterized in that the transparent outer layer (1) is chosen from among the aliphatic polyamides having good UV resistance and capable of sublimation, preferably polyamides 11 or 12. Method according to claim 9 or 10, characterized in that the opaque internal layer (2) is chosen from aliphatic polyamides, copolymers based on polyamide (s) such as polyesteramides, polyetharamides, copolymer compositions based on polyamide and modified polyolefin (s), copolymers of styrene and carboxylic acid or its anhydrous. Method according to claim 9, 10 or 11, characterized in that the bonding film (4) is based on polymers or copolymers of polyethylene or EVA by the action of carboxylic acid, anhydrous carboxylic acid or d 'carboxylic acid ester.

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