EP0774365B1 - Process for decorating composite articles such as skis, surfboards or skateboards - Google Patents

Abstract

The procedure consists of preparing the decorative layer and assembling it with a reinforcing structure of the article, based on a hot-melt resin, during a final hot pressing stage. During a first stage the decoration is transferred by a sublimable ink method to one side (100) of a transparent or translucent plastic material (1). In a second stage a layer of a contrasting material (3) of a non-anodised aluminium, dry natural or synthetic fibres, or wood, e.g. of a non-anodised aluminium foil coated on both faces with an ionomer-type olefin copolymer film. In other variants the contrasting layer can be of a woven or non-woven textile made from glass, carbon, polyester or aramid fibres.

Description

The invention relates to a new method of decorating a composite article. It relates more particularly to articles in the form of laminates combining different plastic and composite materials such as skis in general, surfboards, skateboards and other objects of a similar nature.

Sublimation is a technique well suited for decorating skis, which allows to use many different plastic supports and to print any patterns without it being necessary to subject the support to a preliminary specific preparation operation. The transfer principle consists of evaporate inks contained on a backing paper in the form of extracts dry by applying heat and pressure against the support to be decorated. The process is clean, fast and free from harmful vapors or solvents.

In most cases, the decoration is transferred to the external surface of a transparent layer covering the article to be decorated. An ink gradient is formed over a few tenths of a mm from the outer surface towards the inside of the transparent layer. The major drawback is that the decor is directly subject to external aggression and can be deteriorated quickly if the conditions of use of the article are severe (when the article is subject to shocks, scratches, strong UV radiation, etc.).

We tried to provide solutions to these problems, for example in patent application FR-A-2 620 974 belonging to the applicant where proposes to carry out sublimation through an opaque internal layer secured beforehand by extrusion with a transparent outer layer. The bilayer thus decorated is then attached and then secured to the article.

Patent application FR-A-2 620 975 also belonging to the plaintiff is distinguished from the previous one by the fact that sublimation is first performed on an opaque monolayer sheet which is then assembled by gluing on a transparent single-layer protective sheet. The set is then attached to the article by hot gluing.

In these two cases, the migration of the inks is done through the layer opaque; which creates a loss in the final definition of the decor. Even if the forehead migration more concentrated in ink appears, we obtain a pastellization of the decoration, due to the vertical diffusion of the inks through the opaque layer.

The documents EP-A-606 556 and EP-A-641 575 describe a method of decorating an article composite during which it is assembled hot and under pressure on the decorated side by sublimation, an opaque synthetic fiber sheet (e.g. polyamide).

Other solutions have been tried such as for example carrying out the sublimation through the internal face of the transparent protective layer.

The transparent layer thus decorated is assembled with an opaque layer. The assembly is then secured to the composite article by hot bonding. In this case, the increase in temperature during bonding causes a restart migration of the inks, which then diffuse into the opaque layer. Diffusion in depth creates the aforementioned pastellization problem, which is also associated with significant lateral diffusion due to some heat creep opaque layer; which makes the final decor less clear.

The Applicant has provided a satisfactory solution to this problem of ink migration which is exposed in the unpublished French application n ° 95 00684. It consists in covering the transparent layer sublimated by a transparent coating of crosslinkable material and then proceed curing by crosslinking of the coating to improve its resistance to creep and its thermal stability. This process does not only have advantages.

In particular, the layer of crosslinkable material is preferably chosen from varnishes. It is also necessary to apply a coat of white lacquer or contrasting color over the layer of crosslinkable material.

These products contain highly volatile solvents or diluents, flammable and often harmful. Their safe application for the health of manipulators and for the environment in general, demand the use of means specific.

In addition, it is also necessary to respect drying times or employ means suitable for rapid crosslinking such as UV radiation, for example. The most of the time, it is also necessary to operate surface treatments to improve the adhesion between the different layers.

In a more general way too; due to the presence of a layer of plastic or lacquer contrast, the background effects are not very varied and all lead to a fairly similar rendering.

The object of the present invention is to provide a solution to the problems cited above.

In particular, one of the goals is to offer a decoration solution by internal sublimation which is more ecological by avoiding the use of materials such than solvents, thinners and other similar products.

Another object of the invention is in addition to highlighting the patterns of decoration by very diverse and attractive material effects, such as example, a metallic, woven, screened background effect, etc.

• un premier cycle, au cours duquel on effectue le transfert d'un décor par la méthode d'impression d'encre(s) sublimable(s) sur la première face d'une couche de matière plastique transparente ou translucide ;
• on procède ensuite dans un second cycle au moyen d'un film de collage à l'assemblage à chaud et sous pression sur la première face ainsi décorée, d'une feuille de contraste en matériau choisi parmi le groupe constitué par l'aluminium non anodisé, la fibre sèche naturelle ou synthétique sous la forme d'une nappe ou d'un voile textile non tissé ou tissé, le bois.

For this, the invention relates to a method of decorating a composite article comprising the preparation of a decorated complex to be assembled with a reinforcing structure of the article based on hot-melt resin during a subsequent pressing cycle. hot. He understands:

• a first cycle, during which a decoration is transferred by the printing method of sublimable ink (s) on the first face of a transparent or translucent plastic layer;
• we then proceed in a second cycle by means of a bonding film to the hot assembly and under pressure on the first face thus decorated, of a contrast sheet of material chosen from the group consisting of non-anodized aluminum , natural or synthetic dry fiber in the form of a tablecloth or a non-woven or woven textile veil, wood.

Sublimation inks do not have the ability to migrate into different materials during the final cycle. Thus, the decor remains clean and retains its original colors. These different materials also make it possible to obtain particularly striking and varied background effects.

According to another characteristic of the invention, the contrast sheet is a sheet non-anodized aluminum covered on each side with a film of an olefin copolymer of the ionomer type. The film acts as a bonding interface and makes the aluminum compatible with bonding with most of the substrates with which it is intended to adhere. It also serves as protection against oxidation of the aluminum foil during its storage.

According to another characteristic, a barrier film is approached on the face of the contrast sheet made of natural or synthetic dry fiber material, intended to enter in contact with the flowable resin of the reinforcing structure of the article; said barrier film being chosen from a material with good bonding compatibility with the contrast sheet on the one hand and with the hot-melt resin on the other hand. This prevents the resin from reinforcement structure to cross or impregnate the contrast sheet and create by Consequently, externally visible appearance defects (bubble phenomena, stains, etc.).

According to a characteristic linked to the previous one, the barrier film is approached by taking advantage of the heat and pressure exerted during the second assembly cycle of the sheet contrast on the plastic layer.

In an alternative solution, it can also be provided for the barrier film to come into contact with done during the final assembly of the complex decorated with the reinforcement structure of the article during the subsequent hot pressing cycle.

The invention also relates to the decoration complex intended to be assembled with a reinforcement structure based on hot-melt resin of a composite article.

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

Figure 1 shows the first sublimation transfer cycle of the process of the invention.

Figures 2 and 3 show the second hot and under assembly cycle pressure of the process of the invention.

FIG. 4 shows a diagrammatic section view of a ski covered with the complex of the invention.

Figure 5 is a view similar to Figure 2 according to a variant of the invention.

The implementation of the method according to the invention requires first of all the use a single-layer plastic sheet 1 made of transparent or translucent material; this sheet will be called "transparent layer" in the description below.

On one of the faces 100 of the layer 1, we proceed, in a first step, to an impression of a decor by transfer of sublimable dyes. This face 100 is intended to constitute the internal side of the transparent layer in the complex; as opposed to the opposite face 101 which is the outer side. The reason for decoration to be printed is in a manner known per se contained in a sheet of support paper 4 which is applied under a pressure P at a temperature T for a time t against the face 100 of the transparent layer. Layer transparent can be chosen from the sublimable plastics of Polyamides such as PA11, PA12, PA6.3, PA6.6, etc., Polycarbonates, ABS (Acrylonitrile Butadiene Styrene), transparent AS (Acrylonitrile Styrene) mixed with TPU (Thermoplastic Urethane Elastomer), Polyethylenes Terephthalates (PET).

The thickness of the transparent layer is between 0.2 and 1.1 mm. The sublimation is carried out at a temperature between 160 and 180 ° C, a pressure from 1 to 2 bars for a time between 1mn30sec and 4mn approximately. The depth of the ink migration front through the layer transparent on the internal side is around or slightly greater than 0.20 mm.

During a second step, this layer is brought together transparent 1 with a solid bonding film 2 and a contrast layer 3. The bonding film 2 is brought into contact with the predecorated face 100 and the layer of contrast 3 is brought into contact with the bonding film (Figure 2).

We then proceed to an actual plating phase by increasing pressure and temperature to at least softening point of the film, so to obtain the adhesion of the transparent layer 1 with the contrast layer 3.

In the example illustrated, the contrast layer is a sheet of aluminum not thin anodized 31 covered on each side with a film of ionomer type olefin copolymer (trade name SURLYN®).

The thickness of the aluminum foil is between 15 and 60 µm thickness and the thickness of each film between 10 and 50 μm.

The bonding film is chosen for its adhesive power with the layer transparent 1 and with the contrast layer 3. It is a hot-melt film of thin thickness between a few microns and a few tenths of millimeters.

It is advantageously possible to use a film 2 based on polymer or copolymer grafted by the action of carboxylic acid or carboxylic acid anhydride, by for example by acrylic acid, by methacrylic acid, or by anhydride maleic.

Such a film 2 can in particular be made of grafted polyethylene, for example in polyethylene grafted with maleic anhydride.

This nature of film allows the bonding of most sublimable materials constituting the transparent layer 1 cited above with the layer of contrast in ionomer treated aluminum.

But the film 2 can also consist of a copolymer of ethylene and acetate vinyl (EVA), grafted by the action of carboxylic acid or acid anhydride carboxylic.

For example, the use of a polyethylene film 2 grafted with anhydride maleic allows the bonding of a first polyamide element 1 on a layer of contrast 3 ionomer treated aluminum. According to the invention, one causes the adhesion of the film to the first element 1 by chemical reaction between the maleic anhydride groups grafted to the surface of the polyethylene and polyamide end groups. These groupings exist in weak concentration in the material, but have the particularity of migrating to the extreme surface when extruding the polyamide sheet and are therefore available for reaction. The reaction leads to the substitution of the atom of maleic cycle oxygen through the nitrogen atom of the terminal amine group polyamide and formation of a water molecule. It is necessary to wear the substrates at temperatures above 110 ° C to initiate the reaction. We must therefore press hot, by calendering or pressing, film 6 against the first element 1 to ensure their joining together.

In the example illustrated, the various layers 1, 2 are assembled, 3 as part of a single heating and pressurizing cycle.

Of course, it is conceivable to first carry out a plating of the film 2 on one of layers 1 or 2 and then to operate, in a second step, to the plating of film 2 with the second layer.

The complex thus formed is then ready for use for use in recovery. of a composite article to decorate.

By composite article is meant essentially any laminated object having a reinforcing structure. We think in particular of skis, snowboards, skateboards, etc.

Figure 4 schematically shows the section of a ski which includes a complex obtained according to the process of the invention.

The complex can be joined to the rest of the ski structure in very different processes. In all cases, we proceed generally a hot pressing cycle with the reinforcement structure 4 of the ski based on thermofluable resin. This reinforcing structure 4 can in particular be consisting of a reinforcing textile sheet pre-impregnated with a resin thermosetting or thermoplastic resin.

One can in particular use a reinforcing textile sheet based on woven fibers or non-woven glass, carbon or polyaramide, impregnated with a resin thermosetting wet or partially crosslinked chosen from the group consisting of polyester, epoxies, polyurethanes.

Alternatively, a fiber-based reinforcing textile sheet can be used woven or non-woven glass or carbon impregnated with a resin thermoplastic chosen from the group consisting of polyamides, polycarbonates, PEI (Polyether Imide).

More generally, the contrast sheet 3 can be chosen from among the group consisting of non-anodized aluminum, synthetic dry fiber and wood.

Depending on the choice made, we can obtain either a color rendering metallic in the case of aluminum, either a woven or woven background in the case of fiber, again a veined aspect in the case of wood.

When the contrast sheet is made of dry fibers, it appears in the form of a non-woven or woven textile tablecloth (or veil) made of glass fibers, carbon, polyester, polyaramid or other synthetic fibers or natural, like cotton for example.

In order to avoid any pollution of the dry fiber of the contrast sheet 3 by the thermofluidable resin of the reinforcing structure of the composite article to be decorated, it is necessary to waterproof the outer face 33 with a barrier film 21 (figure 5).

For this, we take advantage during the second cycle to hot plating of the layer transparent pre-sublimated 1 with the contrast sheet 3 by means of the film of bonding 20 to add and adhere an additional barrier film 21 to the external face 33; as opposed to its internal face 32 in contact with the film 20. The collage film 20 plays an important role as a buffer for sublimation inks which tend to want to migrate naturally into the dry fiber layer 3. The barrier film 21 is chosen from a material having good bonding compatibility with contrast sheet 3, on the one hand, and with resin hot melt of the reinforcing structure of the composite article to be decorated, other go.

Alternatively, the barrier film can also be approached during the final assembly of the complex with the reinforcing structure of the article to be decorated during the subsequent hot pressing cycle.

The barrier film 21 can be made of a thermoformable material such than in ionomeric material, preferably dyed in the mass to improve the contrast of sheet 3. The barrier film is chosen from a material whose viscosity is such that it penetrates inside the interstices of the fiber and clogs them.

Another advantage of dry fiber lies in its capacity to avoid, just as much, the lateral creep of the bonding film 20. During the hot assembly cycle, the fiber absorbs part of the molten thermoplastic material due to its porosity.

For example, the use of an ionomer barrier film allows bonding a contrast sheet chosen from the materials mentioned above with the reinforcement structure based on thermofluidable epoxy resin.

The present invention is not limited to the embodiments which have been explicitly described, but it includes various variants and generalizations contained in the scope of the claims below.

Claims (9)

1. Process for decorating a composite article including the preparation of a decorated complex to be assembled to a reinforcement structure (4) of the article made of a resin, capable of flowing when heated, during a subsequent cycle of hot pressing, characterized in that it includes:

   a first cycle, during which the transfer of a decoration is undertaken using the method for imprinting sublimable ink(s) on the first surface (100) of a layer of transparent or translucid plastic material (1);

   a second cycle during which one proceeds, by means of an adhesion film (2, 20), with the hot and press assembly on the first surface thus decorated (100), of a contrast sheet (3) made from a material selected among the group constituted by non-anodized aluminum, natural or synthetic dried fiber in the form of a non-woven or woven fabric or textile web, wood.
2. Decorating process according to claim 1, characterized in that the contrast sheet (3) is a non-anodized aluminum sheet covered on each surface with a film of an ionomer-type olefin copolymer.
3. Decorating process according to claim 1, characterized in that one proceeds with the lining of a barrier film (21) on the surface of the contrast sheet (3) made of a material of natural or synthetic dried fibers, adapted to enter into contact with the resin, capable of flowing when heated, of the reinforcement structure (4) of the article; said barrier film (21) being selected from a material having a good adhesion compatibility with the contrast sheet (3), on the one hand, and with the resin, capable of flowing when heated, on the other hand.
4. Decorating process according to claim 3, characterized in that the lining of the barrier film (21) is done by taking advantage of the heat and pressure exerted during the second cycle for assembling the contrast sheet (3) on the plastic material layer (1).
5. Decorating process according to claim 3, characterized in that the lining of the barrier film (21) occurs during the final assembly of the decorated complex with the reinforcement structure (4) of the article during the subsequent cycle of the hot pressing.
6. Decorating process according to claim 3, 4 or 5, characterized in that the contrast sheet (3) is presented in the form of a non-woven or woven textile fabric made of glass fibers, carbon, polyester or polyaramid or cotton.
7. Decorating complex adapted to be assembled with a reinforcement structure made of a resin, capable of flowing when heated, of a composite article, said complex comprising:

   a transparent plastic material layer (1) whose inner surface (100) bears a decoration obtained by the method for imprinting sublimable ink(s);

   a contrast sheet (3) that covers the inner surface (100) of the transparent plastic layer (1), characterized in that:

      the contrast sheet (3) is assembled to the surface (100) of the plastic layer (1) by means of an adhesion film (2) and in that the contrast sheet (3) is selected from the group constituted by non-anodized aluminum, natural or synthetic dried fiber in the form of a non-woven or woven fabric or textile web, and wood.
8. Decorating complex according to claim 7, characterized in that the contrast sheet is a non-woven or woven textile fabric made of glass fiber, carbon, polyester or polyaramid.
9. Composite article of the ski or snowboard type provided with a decorating complex according to claim 7 or 8.

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