EP0722843B1 - Method of decorating an article by sublimation - Google Patents

Abstract

The procedure, consists of preparing a decorative complex (5) which is then attached to the article being decorated by means of adhesive or hot moulding. The decoration is transferred by printing with a sublimable ink on the first surface of a layer of plastic (1), which is then covered with a transparent coating (2) of a material which can be reticulated. The coating is then hardened to increase its resistance to creep and its thermal stability before covering with a second layer of plastic (3). The transparent coating (2) is selected from varnish, pigment-free silk-screen printing ink, adhesive coatings or reactive glues, or films of thermoplastic or thermo-setting material. The coating is applied in a liquid or very slightly viscous form by curtain, spray gun, roller or silk-screen printing, and it is hardened by heating, UV irradiation or infra-red irradiation. Plastics suitable for the coating include, for example, ABS, acrylonitrile styrenes, mixed or not with thermoplastic urethane elastomer, styrene copolymers such as styrene and maleic anhydride copolymer, or polybutadiene terephthalates.

Description

The present invention relates to a method of decorating an article by sublimable ink printing method (s). It no longer applies particularly to articles in the form of laminates grouping together different plastic and composite materials such as skis in general, surfboards, skateboards and other similar objects.

Sublimation is a technique well suited for decorating such items that allow the use of many different plastic supports and print any designs without the need to submit the support for a preliminary specific preparation operation. The principle of transfer consists in evaporating inks contained on a support paper under form of dry extracts by application of heat and pressure against the support to decorate. The process is clean, rapid and without the release of vapors or harmful 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 takes place through the opaque layer; which creates a loss in the final definition of the decor. Even if the front of migration more concentrated in ink appears, we obtain a pastellisation of the decoration, due to the vertical diffusion of the inks through the opaque layer.

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 object by hot bonding. In that case, the increase in temperature during bonding causes a restart of the migration of the inks, which then diffuse in 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.

Document EP-A-0 421 140 relates to a method of decoration and covering of substrates; for example wooden products of the furniture type kitchen or office. It consists in impregnating a sheet presublimated in fibrous material by a pre-crosslinked solution of melanin resin and / or urea-formaldehyde. Then this sheet is heated, molded with the substrate by application of temperature and pressure so as to obtain crosslinking full of resin. This resin which serves as a protective covering must have qualities of resistance to scratching, stretching and others. However for an effective action, such a covering must in principle be of a thickness that is difficult to obtain by impregnation. Such protection is generally insufficient. Melanin and / or urea-formaldehyde resins are known generally for their ability to bond with cellulose-based materials, such as wood, plywood, chipboard, and other cellulose derivatives. In however, they are not very compatible with bonding with most materials plastics used in the composition of composite laminates such as skis, surfboards and the like.

Document EP 0 625 433 applies to the manufacture of supply elements and furniture; such as cupboards, etc. The method is to produce a decorative cover sheet based on polystyrene or polyolefin decorated by ink transfer (gravure, sublimation, etc.). After transfer, the sheet undergoes a varnishing operation by which the layer of varnish protects the transferred design, then the sheet is applied for example by adhesives to the filler core of the supply element. In this case too, the varnish has for essential role of ensuring the protection of the decoration. Such a means may prove to be sufficient for interior furniture; however, it does not provide protection sufficient for a product subject to very harsh external conditions, such as skiing for example. Resistance to edges or club blows from a protective varnish is notoriously insufficient. Resistance to conditions of the unprotected varnish is weak and leads to hardening and premature aging. The varnish quickly loses its initial appearance and its covering and protective power.

Document CH-A-542042 relates to a traditional process for transferring continuous of a transparent plastic strip serving as a protective coating on a non-textile substrate (synthetic leather, plastic, etc.).

The document EP-A-033 776 relates to a process which consists in obtaining two steps a top cover of a ski printed from a sheet of polyethylene or PTFE. First, the sheet is heated and then high temperature and high pressure contact with a print containing sublimable and diffusable pigments. The second step is to control the cooling temperature to produce a solidification without distortion and obtain pigment stability.

Document JP-A-55114589 relates to a method of decorating a sheet of inorganic or metallic material. We apply a solution of colloidal mixture of alumina and / or silicate and a melamine resin on the face printed from said sheet. This coating is resistant to abrasion and external conditions and therefore serves as protection of the decor.

This solution is not applicable for the recovery of compounds carbon-based organics such as plastics of which it is essentially matter in the present invention.

The object of the present invention is to provide a solution to the problems aforementioned encountered in the field of decorating articles in the form of laminates such as skis, snowboards or other objects of a similar nature which are mainly made of materials derived from carbon chemistry (plastics, foams, elastomers, etc.). In particular, one of the goals is to achieve a decoration by sublimation on a face protected from external aggressions and which retains its original colors and perfect clarity even after bonding to hot and pressurized complex decorated on the rest of the article.

• on effectue le transfert d'un décor par la méthode d'impression d'encre (s) sublimable (s) sur la première face d'une première couche de matière plastique ;
• on procède au recouvrement de ladite première face ainsi décorée par un revêtement transparent en matière réticulable ;
• on procède au durcissement par réticulation dudit revêtement pour améliorer sa résistance au fluage et sa stabilité thermique en vue de l'assemblage ultérieur du complexe avec le reste de l'article à décorer ;
• enfin, on procède à l'assemblage sur le revêtement transparent d'une seconde couche de matière plastique.

For this, the invention relates to a method of decorating an article made of composite materials, in particular a ski, a snowboard or a skateboard, comprising the preparation of a decorated complex which is then assembled with the article. by gluing or hot molding, during which:

• a decoration is transferred by the printing method of sublimable ink (s) on the first face of a first layer of plastic material;
• the first surface thus decorated is covered with a transparent coating of crosslinkable material;
• curing is carried out by crosslinking said coating to improve its creep resistance and its thermal stability with a view to subsequent assembly of the complex with the rest of the article to be decorated;
• finally, we proceed to the assembly on the transparent coating of a second layer of plastic.

By doing so, we do not prevent the migration of inks, however we allows this migration to take place through the crosslinked transparent coating; which has no effect on the final color of the decor (we thus solve the pastelization problem). Likewise, the crosslinked coating has resistance to hot creep which is significantly improved, which prevents any lateral diffusion inks which can create a lack of clarity during subsequent operations of bonding or molding using high temperatures and high pressures.

According to an additional characteristic of the invention, the coating transparent is chosen from varnishes, serigraphy inks without pigment, adhesive coatings or reactive adhesives, thermoplastic films or thermosetting.

The main property retained for the choice of these coatings is their good resistance to hot creep after crosslinking and their ability to remain equally transparent.

According to another characteristic, an application of the coating is carried out. liquid or very slightly viscous state by means of application of the type to curtain, roller, spray or screen printing on the first side of said layer.

According to another characteristic, the hardening of the coating by crosslinking is carried out by heating, by irradiation with UV rays, or by irradiation with IR rays. Thus a wide choice is possible which depends on the nature of the transparent coating chosen. In particular, crosslinking with UV rays presents the advantage of consuming little energy.

According to another characteristic, said first layer is chosen from among the transparent sublimable plastics which constitute the outer layer of protection of the decorated complex and in that after the completion of the third hardening step of the transparent coating, assembly is carried out on the transparent coating of the second layer consisting of an undercoat of contrast chosen in an opaque material on the transparent coating. The contrast underlay reveals the full intensity and depth of the decoration through the transparent layer and its coating. Moreover, the inks do not migrate into the opaque layer due to the presence of hardened transparent coating and the decor remains clear and perfectly contrasted whatever the next steps are.

According to an additional characteristic, the adhesion of the undercoat is carried out contrast on the transparent coating by interposing a solid film of bonding and hot pressing.

According to an alternative, the contrast undercoat is chosen from lacquers or pigmented varnish and is deposited in a liquid state on the transparent coating hardened. This method is appreciated for its simplicity and the economical aspect.

According to a second alternative, the contrast sublayer is chosen from solid bonding films having good adhesion properties with the hardened transparent coating on the one hand and with the rest of the article on which it is intended to be reported on the other hand and in that one obtains its membership by hot pressing.

According to another characteristic, said first layer is chosen from among the opaque sublimable plastics which constitutes the sub-layer of contrast of the decorated complex and in that after the hardening of the transparent coating, we proceed to the assembly of a second layer constituting the protective layer of the complex, chosen from plastic material transparent, on the transparent coating covering the contrast underlay.

The advantage of such a characteristic is that one can choose from transparent protective layers, some materials that are not necessarily suitable for sublimation but which can have other advantages, as better resistance to scratching or solvents or even be more economic.

According to a characteristic linked to the previous one, the adhesion of the protective layer on the transparent coating by interposing a solid film bonding agent with good adhesion properties with the protective layer on the one hand and with the hardened transparent coating on the other.

• Les figures 1 à 6 illustrent un premier mode de réalisation de la décoration d'un article selon le procédé de l'invention ;
• Les figures 7 et 8 illustrent une variante des étapes d'assemblage final sur l'article selon le premier mode de réalisation des figures 1 à 6 ;
• Les figures 9 à 15 illustrent un second mode de réalisation ;
• Les figures 16 et 17 illustrent un exemple non limitatif de la conformation d'un dessus de ski décoré comprenant le complexe réalisé selon le procédé de l'invention ;
• Les figures 18 et 19 illustrent une variante dans laquelle on procède à la décoration d'un objet en matière plastique injectée 'en moule', à l'aide d'un complexe prédécoré selon l'invention.

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 6 illustrate a first embodiment of the decoration of an article according to the method of the invention;
• Figures 7 and 8 illustrate a variant of the final assembly steps on the article according to the first embodiment of Figures 1 to 6;
• Figures 9 to 15 illustrate a second embodiment;
• Figures 16 and 17 illustrate a non-limiting example of the configuration of a decorated ski top comprising the complex produced according to the method of the invention;
• Figures 18 and 19 illustrate a variant in which one proceeds to the decoration of a plastic object injected 'in mold', using a predecorated complex according to the invention.

The realization of the first mode of figures 1 to 6, requires first of all the use of a monolayer plastic sheet (1) made of transparent material or translucent; this sheet which will be called "transparent layer" in the description below.

On one of the faces (100) of the layer (1) which will subsequently constitute the face internal of the complex as opposed to the opposite external face (101), we proceed, in a first step, to an impression of a decoration by transfer of dyes sublimable. The decoration pattern to be printed is in a manner known per se in a sheet of backing paper (4) which is applied under pressure (P) to a temperature (T) for a time (t) against the face (100) or internal face of the transparent layer. The transparent layer can be chosen from the materials polyamide sublimable plastics such as PA11, PA12, PA6.3, PA6.6, etc, Polycarbonates, ABS (Acrylonitrile Butadiene Styrene), AS (Acrylonitrile Styrene) transparent mixed with a TPU (thermoplastic urethane elastomer), Polyethylene Terephthalates (PET).

The thickness of the transparent layer is between 0.2 and 1.1 mm. This thickness is chosen sufficient to provide sufficient protection to scratches of all kinds (edges, sticks, shocks, etc.). Sublimation is operated at a temperature between 160 and 180 ° C, a pressure of 1 to 2 bars for a time between 1 min 30 sec and about 4 min. The depth of ink migration front is around or slightly greater than 0.20 mm.

In Figure 3, the next or second step is to cover the layer thus predecorated by a transparent or translucent coating (2) in crosslinkable material, hereinafter called "transparent coating". From materials likely to be suitable, one can quote single or two-component varnishes Epoxy or Polyurethane type, non-pigmented screen printing inks, certain two-component adhesive coatings or reactive adhesives or certain crosslinkable transparent solid films of the polyethylene or ionomer type.

The covering of the face (100) by the coating can be achieved by different means adapted according to the type of coating. For varnishes or for certain liquid adhesives, automatic means can be used application to the curtain, roller or manual means such as passage to the pistol. For screen printing inks, the application will be done using of the screen printing technique. For some solid films, it will suffice to make a hot plating of the film on the face of the transparent layer by means adapted. In the latter case, the crosslinking is obtained simultaneously during the plating by increasing the crosslinking temperature of the constituent resin the film.

In other cases, crosslinking is obtained in a third step by heating in the oven or by radiation under IR or UV lamps, for example (figure 4). The purpose of crosslinking is to modify the state of the coating to bring it to an irreversible hardening state allowing it to remain stable thermally and withstand hot creep in later stages of pressure cooking necessary for assembling the decorated complex on the article itself; these stages generally taking place in a mold at pressures around 7 to 10 bars approximately, and at temperatures between 60 and 150 ° C.

Sublimation inks are likely to migrate inside the coating during this crosslinking phase in a small proportion, which does not affect the precision and colors of the decor.

After the coating (2) has hardened, an underlay is assembled of contrast (3) on the coating itself. The underlay (3) is rendered opaque by pigmentation, preferably in white for example by means of titanium dioxide incorporated during manufacture. Relative to the pigmentation of the contrast underlay which is intended to reveal the decor, it is necessary to specify that we are by no means limited to the color white. For example, range of clear, metallic or pearly shades.

The contrast layer (3) can be chosen from lacquers or varnishes pigmented; and in this case, the deposit is made in the liquid state on the coating (2) already hardened. You can then either let it dry at room temperature or activate the drying by heating for example. We then obtain the complex (5) of FIG. 5. This complex is then reported on the article and adhesion can be done using a solid bonding film (7) between the article (6) and the opaque undercoat (3) of the complex (5), by applying a sufficient temperature and pressure, as in mold for example. Besides its role as an adhesive, the film has the function secondary to absorb the structural irregularities of the reinforcements on the face of article contact. Thus the top of the decorated complex retains its appearance smooth after adhesion on the article.

The contrast layer can also be a solid opaque bonding film. which will be chosen for its properties of compatibility with bonding with the coating (2) and with the surface of the article on which it is intended to come into contact.

The contrast layer can also be a simple opaque layer of material. plastic having no adhesion compatibility with the coating (2) or with the rest of the article (6). In this case, the assembly can be done by interposing solid bonding films (70, 71) between the coating (2) and the opaque layer (3) on the one hand, and between the opaque layer (3) and the rest of the article (6) on the other. In this case, provision can be made for the various layers to be assembled during a single stage of hot and pressure assembly in a mold (Figures 7 and 8). In any case, this subsequent molding step does not affect the quality of the sublimated decor thanks to the principle of the invention implemented before.

It is shown in FIG. 8 in particular that the transparent layer (1) has an external face (101) in contact with the external environment and a face internal (100) which has been printed, but which is sheltered from the external environment. The crosslinked coating (2) is also protected by the thickness of the layer transparent. In reality, it has no specific protective function for the decor.

• Des Styréniques tels que les ABS (Acrylonitrile Butadiène Styrène) ou AS (Acrylonitrile Styrène) opaques mélangés ou non à un TPU (Elastomère Thermoplastique uréthane),
• Des Copolymères de Styrène et d'acide ou d'anhydride d'acide carboxylique tels que le SMA (copolymère de Styrène et d'anhydride maléique),
• Des PBT (Polybutadiènes téréphtalates).

A second embodiment is illustrated in FIGS. 9 to 15. The first layer is chosen from among the opaque sublimable plastics, to subsequently constitute the contrast sublayer (30). These plastics are preferably chosen from the group consisting of:

• Styrenics such as ABS (Acrylonitrile Butadiene Styrene) or AS (Acrylonitrile Styrene) opaque mixed or not with a TPU (Thermoplastic Urethane Elastomer),
• Copolymers of Styrene and of carboxylic acid or anhydride such as SMA (copolymer of Styrene and maleic anhydride),
• PBT (Polybutadienes Terephthalates).

All these materials have the distinction of having a low penetration of deep inks, resulting in better color rendering.

One of its faces (300) is transferred to a decoration by sublimation. by means of a backing paper (40) under suitable heating conditions and pressure (Figures 9 and 10).

The next step is to cover the face (300) thus decorated with the opaque layer by transparent or translucent coating of crosslinkable material (2) as described in the previous mode (Figure 11), and we proceed to its crosslinking (Figure 12).

After this third step, a protective layer is assembled transparent (10) on the coating (2) covering the opaque layer (30) at the by means of a solid bonding film (72), itself chosen from transparent material and suitable for bonding both with the opaque layer and with the coating (2) in appropriate heat and pressure conditions (Figure 14). The complex (50) as well formed can be added to the rest of the article to be decorated (6) by means of a second bonding film (73) for example (Figure 15).

Of course, the assembly or bonding phases of the different components can be integrated into a more complex molding process used in the production of composite articles such as skis modern for example.

Figures 16 and 17 illustrate an example of assembly of a complex decorated (5, 50) as previously manufactured, with the upper reinforcement element (8) for the manufacture of a ski.

In a hot forming mold comprising a lower die (9), has a stack of layers intended to form the top of the ski; the complex pre-decorated (5, 50) according to the invention, a layer (8) intended to form the reinforcement upper of the ski and a solid film (74) compatibilizing intended to ensure the bonding from above with the rest of the ski.

The reinforcing layer (8) consists of one or more textile plies of reinforcement pre-impregnated with a thermosetting or thermoplastic resin. In the case of a reinforcement in a textile sheet pre-impregnated with a thermosetting resin, the hot pressing operation ensures crosslinking or the complement of crosslinking of the resin and the adhesion of the film (74) to the reinforcement (8). After hardening, the top thus formed can be removed.

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

The manufacturing process is described more precisely in the application for Patent No. 2,654,644 belonging to the plaintiff. It does not of course constitute that a nonlimiting example and is only given to illustrate the integration of the invention in the more general context of ski manufacturing.

The pre-decorated complex (5) can also be used to cover, at least partially an injected plastic object. In this case, we provide a complex pre-decorated (5) as previously obtained. We have this complex in the cavity of an injection mold (90) so that the transparent layer (1) either in contact with one of the internal walls of the mold cavity. We inject under pressure in the remaining volume of the mold cavity a thermoplastic material in such a way that it fills the entire volume. The molten material depositing on the face of the opaque layer (3); which causes the adhesion of the complex with the mass injected. In Figure 18, there is shown a single nozzle injection (900) but of course, the mold could have more. After cooling, the mold (90) is opened and the object which has on one of its faces, at least, the predecorated complex (5) (Figure 19). This method is particularly well suited for decorating plastic articles like tip tips or ski heels, or other attachments on a ski or a surf.

Claims (10)

1. Decorating process for an article made of composite materials, in particular a ski, a snow board or a skate board, including the preparation of a decorated complex (5, 50), which is then assembled with the article by glueing or by hot molding, during which:

   the transfer of a decoration is done by the method of printing sublimable ink(s) on the first surface (100, 300) of a first layer of plastic material (1, 30);

   said first decorated surface is covered by a transparent coating (2) made of a cross-linkable material;

   said coating (2) is hardened by cross-linking to improve its resistance to creeping and its thermal stability for the subsequent assembly of the complex (5, 50) with the rest of the article (6) to be decorated;

   finally, a second layer of plastic material (3, 10) is assembled on the transparent coating (2).
2. Decoration process according to claim 1 ,characterized in that the transparent coating (2) is selected from among varnishes, non-pigmented serigraphy inks, adhesive coatings or reactive glues, films of thermoplastic or thermosetting material.
3. Decoration process according to claim 2, characterized in that said coating is applied while in liquid or very low viscous state by application means of the curtain, gun or roller type, or by serigraphy on the first surface (100, 300) of said layer (1, 30).
4. Decoration process according to claim 3, characterized in that the hardening of the coating by cross-linking is done by heating, irradiation of UV rays or irradiation of IR rays.
5. Decoration process according to any of claims 1-4, characterized in that said first layer (1) is selected from among the sublimable transparent plastic materials and constitutes the outer protective layer of the decorated complex (5), and in that after the hardening of the transparent coating (2), the second layer, constituted by a contrast undercoat (3) chosen in an opaque material, is assembled on the transparent coating (2).
6. Decoration process according to claim 5, characterized in that the adhesion of the contrast undercoat (3) on the transparent coating (2) is done by inserting solid adhesive film (70) and by hot pressing.
7. Decoration process according to claim 5, characterized in that the contrast undercoat (3) is selected from among pigmented lacquers or varnishes and is laid while in liquid state on the hardened transparent coating (2).
8. Decoration process according to claim 5, characterized in that the contrast undercoat (3) is selected from among the solid adhesive films having good adhesive properties with the hardened transparent coating (2), on the one hand, and with the rest of the article (6) on which it is adapted to be attached, on the other hand, and in that its adhesion is obtained by hot pressing.
9. Decoration process according to claim 1, 2 or 3, characterized in that we choose said first layer is selected from among the opaque sublimable plastic materials (30) and constitutes the contrast undercoat of the decorated complex (50), and in that after the hardening of the transparent coating (2), a second layer constituting a protective layer (10) of the complex, chosen in transparent plastic material is assembled, on the transparent coating covering the contrast undercoat (30).
10. Decoration process according to claim 9, characterized in that the adhesion of the protective layer (10) on the transparent coating (2) is done by inserting a solid adhesive film (72) having good adhesion properties with the protective layer (10), on the one hand, and with the hardened transparent coating (2), on the other hand.

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