METHOD FOR MANUFACTURING A THREE-DIMENSIONAL ARTICLE WITH METALLIC MOTIF(S)

Abstract

Method for manufacturing a three-dimensional article with metallic pattern(s) The invention relates to a method for manufacturing a three-dimensional article comprising at least one metallic pattern, comprising at least: a step A of supplying a flat substrate of thermoformable material; a step B of forming on a surface of the flat substrate a temporary masking coating which adheres to said surface, to obtain a masked substrate having at least one unmasked area; a step C of thermoforming the flat substrate to give it a general three-dimensional shape; a step D of metallizing the substrate to form a metallic deposit on it; and a step E of removing said temporary masking coating. Method for manufacturing three-dimensional articles with metallic pattern(s). Figure for the abstract: Fig. 3.

Description

Title of the invention: METHOD FOR MANUFACTURING A THREE-DIMENSIONAL ARTICLE WITH METALLIC PATTERN(S)

[0001] The present invention relates to the general technical field of three-dimensional articles provided with metallic pattern(s), decorative) and / or functional.

[0002] The invention relates more specifically to a method for manufacturing a three-dimensional article comprising at least one metallic motif.

[0003] In the field of manufacturing objects decorated with metallic patterns, processes are already known for creating or applying metallic patterns to the surface of a three-dimensional semi-finished object, such as, for example, a glass or plastic bottle or flask, using additive techniques (for example, screen printing or pad printing with metallic ink, or the application of a metallic film by hot stamping) or subtractive techniques (for example, metallizing the surface of the object followed by selective laser engraving). Although these techniques allow for particularly attractive decorative effects, they are nevertheless costly and difficult to implement for large patterns.Furthermore, they are very difficult, if not impossible, to apply to the decoration of three-dimensional semi-finished objects with complex geometry / topography, so they are generally only implemented on substantially flat or cylindrical surface portions of prefabricated three-dimensional semi-finished objects.

[0004] In the field of printed electronics, there are known methods for manufacturing three-dimensional articles or objects locally coated with electrically conductive metallizations, in which conductive patterns are produced on a thermoplastic polymer substrate by direct printing (screen printing or inkjet printing) using an electrically conductive ink, such as, in particular, an ink loaded with silver particles. A heat and / or actinic treatment is then applied to remove a solvent contained in the ink and / or to crosslink a polymeric matrix of the ink. The substrate is then thermoformed to give it the desired three-dimensional appearance.Besides the fact that the implementation of an electrically conductive ink is relatively expensive, the electrical performance of the conductive patterns obtained using such an ink remains imperfect, particularly in terms of the level and homogeneity of electrical conductivity, which in some cases can prove problematic for the proper functioning of an electronic device incorporating such a three-dimensional object.

[0005] The objects assigned to the invention therefore aim to provide a response to the aforementioned needs and problems, and in particular to propose a new process enabling the simple and efficient manufacture of three-dimensional articles with decorative and / or functional metallic pattern(s), in a wide variety of shapes and geometries.

[0006] Another object of the invention aims to propose a new process which makes it possible to manufacture three-dimensional articles with metallic pattern(s) of all dimensions.

[0007] Another object of the invention aims to propose a new process which makes it possible to manufacture three-dimensional articles with metallic pattern(s) quickly and relatively cheaply.

[0008] Another object of the invention aims to propose a new method for manufacturing three-dimensional articles with metallic pattern(s) which is simple to implement.

[0009] Another object of the invention aims to propose a new method for manufacturing three-dimensional articles with metallic pattern(s) which can be implemented industrially.

[0010] Another object of the invention aims to propose a new method for manufacturing three-dimensional articles in which the metallic pattern(s) is / are capable of being fine, precise and complex.

[0011] Another object of the invention aims to propose a new method for manufacturing three-dimensional articles whose metallic pattern(s) is / are particularly resistant to external aggressions.

[0012] Another object of the invention aims to propose a new method for manufacturing three-dimensional articles whose metallic pattern(s) is / are particularly homogeneous and regular, both in terms of thickness and in terms of surface appearance.

[0013] Another object of the invention aims to propose a new method for manufacturing three-dimensional articles with metallic pattern(s) which allows excellent control of the shape of the metallic pattern(s).

[0014] The objects assigned to the invention are achieved using a method for manufacturing a three-dimensional article comprising at least one metallic motif, comprising at least: - a step A of supplying a flat substrate made of thermoformable material; - a step B of forming on a surface of the flat substrate a temporary masking coating which adheres to said surface, to obtain a masked substrate having at least one unmasked area; - a step C of thermoforming the flat substrate to give it a general three-dimensional shape; - a step D of metallization of the substrate to form a metallic deposit on the latter; - and a step E of removing said temporary masking coating.

[0015] Other features and advantages of the invention will become apparent and will be described in more detail upon reading the following description, with reference to the accompanying drawings, which are given solely by way of illustrative and non-limiting examples, including:

[0016] [Fig-1] illustrates, in the context of a first example of implementation of a method according to the invention for the manufacture of a three-dimensional RFID antenna, a flat substrate whose surface is covered with a temporary masking coating which adheres to said surface, thus forming a masked substrate having at least one unmasked area, intended to receive a metallic deposit;

[0017] [Fig.2] illustrates a thermoformed masked substrate, obtained after subjecting the masked flat substrate of [Fig.1] to a thermoforming step according to the invention;

[0018] [Fig.3] illustrates a thermoformed substrate whose surface is provided with a solid silver metallic pattern forming an RFID antenna electrode, obtained after having subjected the masked thermoformed substrate of [Fig.2] to a metallization step and a step of removing the temporary masking coating in accordance with the invention;

[0019] [Fig.4] illustrates, in the context of a second example of implementation of a process according to the invention for the manufacture of a three-dimensional article with decorative metallic patterns, a flat substrate whose surface is covered with a temporary masking coating which adheres to said surface, thus forming a masked substrate having at least one unmasked area, intended to receive a metallic deposit;

[0020] [Fig.5] illustrates a metallized masked substrate, obtained after subjecting the flat masked substrate of [Fig.4] to a metallization step and a temporary masking coating removal step according to the invention;

[0021] [Fig.6] illustrates a thermoformed metallized substrate whose surface is provided with a plurality of decorative solid silver metal motifs, obtained after subjecting the flat masked metallized substrate of [Fig.5] to a thermoforming step according to the invention.

[0022] The invention relates to a method for manufacturing a three-dimensional article comprising at least one metallic motif (or "metallic motif"). For the purposes of this invention, "three-dimensional" means a physical object that extends substantially in three dimensions of space, along non-negligible distances from one another. The shape and dimensions of the metallic motif(s) are not particularly limited and may, in particular, depend on the intended application of the three-dimensional article and the metallic motif(s) it bears. Advantageously, the metallic motif(s) in question is / are decorative and / or functional, and thus forms or contributes to forming, for example, but not limited to, one or more circuits printed materials, one or more integrated circuits on a semiconductor substrate, one or more sensor / detector electrodes, one or more electrodes of an electrical heating / defrosting device, one or more radio frequency antennas (WiFi®, RFID, etc.), one or more encoding pictograms capable of being read by electronic devices, one or more figurative and / or scriptural pieces of information identifying a product which incorporates or to which said three-dimensional article is associated, including a commercial product, such as a decorative visual or design on packaging, on an automotive product, etc.

[0023] The manufacturing process according to the invention comprises at least the following steps: - a step A of supplying a flat substrate made of thermoformable material; - a step B of forming on a surface of the flat substrate a temporary masking coating which adheres to said surface, to obtain a masked substrate having at least one unmasked area (temporary "selective" masking coating); - a step C of thermoforming the flat substrate to give it a general three-dimensional shape; - a step D of metallization of the substrate to form a metallic deposit on the latter; - a step E of removing said temporary masking coating.

[0024] Thanks to the process according to the invention, which ingeniously proposes to form a temporary (selective) masking coating adhering to the surface of a flat substrate made of thermoformable material, prior to a thermoforming step of this flat substrate, for the purpose of selective metallization of the substrate, it becomes advantageously possible to manufacture, in a particularly simple and efficient manner, three-dimensional articles with decorative and / or functional metallic pattern(s), in a wide variety of shapes and geometries. Indeed, in practice, it proves to be much easier to perform temporary masking on a flat substrate than on a three-dimensional substrate, especially one with a complex shape / geometry, and the use of such a temporary masking coating then makes it possible to easily and precisely metallize a wide variety of thermoformable material substrates, according to a plurality of possible metallization techniques.

[0025] The invention covers various embodiments, as will be understood from the following, which are based on the general principle of using a temporary (selective) masking coating formed on the flat substrate and adhering to its surface to delimit specific areas of the substrate which, at the end of the process, will bear one or more metallic patterns. In some cases, the temporary masking coating may be intended to allow selective activation of the The substrate surface is exposed so that only at least one area of ​​the substrate surface not masked by the temporary masking coating will be activated and can, during the metallization step D, receive a metallic deposit to form one or more metallic pattern(s). In other cases, particularly when it is not necessary to activate the substrate surface to allow for its subsequent metallization, the metallization step D may constitute a metallization step of the masked substrate to form a metallic deposit on it, at least on the said unmasked area. After the removal of the temporary masking coating in step E, only this unmasked area will bear a metallic deposit forming, or intended to form, the desired metallic pattern(s).

[0026] The process may also optionally include, in particular, all or part of the following additional steps (and not necessarily in the following order): - at least one step F for preparing the surface of the substrate; - a step G of defining a two-dimensional masking pattern, according to which the temporary masking coating is then formed on the surface of the flat substrate during step B, from a modeling of a deformation of the flat substrate during step C of thermoforming and a representation of the metallic pattern(s) to be obtained on the surface of the thermoformed substrate; - a step H of activation of the surface of the substrate, in particular of the unmasked area(s) intended to bear the metallic motif(s); - a step I of rinsing the surface of the metallized substrate; - a step J of drying the surface of the metallized substrate; - one or more K, L, M finishing treatment steps of the surface of the metallized substrate, and / or more specifically of the metallic deposit or of the metallic pattern(s) formed on the latter; - a step N of overmolding the thermoformed substrate; - a step O of assembling additional components.

[0027] For the purposes of the invention, a "flat substrate" advantageously means a substrate of generally substantially two-dimensional shape, that is to say, extending essentially in two of the three spatial directions, and to a lesser extent in the third spatial direction. Typically, such a flat substrate can thus take the form of a film, a sheet, or a plate. A "thermoformable material" advantageously means a material that can be shaped, deformed, by heating, that is to say, a material that can be given a particular shape after being brought to a suitable temperature (forming temperature) to soften it, and which retains, after cooling and hardening, the shape thus given to it. If the flat substrate does not already exist prior to the implementation of the process according to the invention, step A of supplying the flat substrate (hereinafter referred to as "step A") may then include the fabrication of such a flat substrate from a chosen thermoformable material. Generally, and depending on the intended applications, the flat substrate may be made of a non-conductive / dielectric thermoformable material, a semi-conductive thermoformable material, or a conductive thermoformable material (either inherently or as a result of a treatment that has rendered it conductive).

[0028] Step B of the formation of the temporary masking coating (or “temporary protective coating”) (hereinafter referred to as “step B”) aims, as introduced above, to delineate on the surface of the substrate one or more specific area(s) which, not having been masked by the temporary masking coating, will bear the desired metallic pattern(s) after the metallization step D, the thermoforming step C, and the removal step E of the temporary masking coating. Conversely, the area(s) of the substrate that were previously masked by the temporary masking coating will be devoid of metallic deposit, and therefore of metallic pattern(s), after the metallization, thermoforming, and removal steps of the temporary masking coating.For the purposes of this invention, a temporary masking coating is a coating that adheres to the substrate surface, either directly to the bare surface of the substrate, or possibly indirectly via an intermediate coating that adheres to the substrate surface and to which the temporary masking coating then adheres. In any case, the temporary masking coating is therefore not a mechanical mask / stencil (such as a screen printing mask, for example) that is simply applied, pressed, or in contact with said surface.

[0029] The thermoforming step C (hereinafter abbreviated as "step C") generally consists of hot-forming the flat substrate, advantageously in a controlled manner, to give it a generally three-dimensional shape, advantageously predefined. In particular, step C aims to deform the flat substrate at least locally and at least in a direction secant to a mean plane of extension of said flat substrate.

[0030] According to one variant (hereinafter, “variant VI”), the thermoforming step C is carried out before the metallization step D.

[0031] According to a first sub-variant (hereinafter, "Via variant") of this variant VI, thermoforming step C is further preferentially carried out before step E of removing the temporary masking coating. In this case, step C is therefore a thermoforming step of the masked, as yet unmetallized, flat substrate, during which the flat substrate and the temporary masking coating are simultaneously thermoformed (or thermodeformed), prior to carrying out step D of metallizing the masked substrate thus thermoformed. As such, the coating of The temporary masking material is therefore itself advantageously thermoformable, or at least thermodeformable, so that it can undergo elongation and thus follow the deformation of the flat substrate, while adhering to its surface during thermoforming step C. The temporary masking coating is thus advantageously designed, particularly in terms of its elongation / deformation capacity without breakage, to withstand the conditions of thermoforming step C of the flat substrate without significantly degrading its surface masking function.Thus, while the shape and / or surface area of ​​the unmasked area(s) may be modified by thermoforming step C, the temporary masking coating remains essentially cohesive and film-forming, so that no additional unmasked areas are unintentionally generated by the deformation of the temporary masking coating during thermoforming step C. For simplicity, the term "unmasked area(s)" will refer indiscriminately in the following to one or more unmasked areas of the masked substrate, whether the latter is thermoformed or not.

[0032] According to a second sub-variant (“variant Vlb”) of this variant VI, step C is carried out after step E, which removes the temporary masking coating, for example, where said temporary masking coating is intended to allow selective activation of the substrate surface during an activation step H prior to metallization step D. In this case, step C is therefore a thermoforming step of the flat substrate, which is free of said temporary masking coating and not yet metallized, prior to carrying out step D, which metallizes the substrate thus thermoformed.

[0033] Insofar as, according to this variant VI, the metal deposit is thus formed on the surface of the substrate after the latter has been thermoformed, the metal deposit does not undergo the mechanical deformation and heating to which the flat substrate is subjected during step C of thermoforming. It is therefore advantageously possible to manufacture a three-dimensional article with particularly pronounced and / or complex shapes and geometries, thus requiring significant deformation of the flat substrate during thermoforming, without the risk that step C will lead to a degradation (delamination, (micro)cracking, etc.) of the quality of the metal deposit, and in particular of its electrical conductivity properties. It becomes particularly advantageous to subject the flat substrate to a deformation rate greater than or equal to 200% during step C of thermoforming.Such a variant VI proves particularly advantageous in the case where one wishes to obtain a three-dimensional article comprising one or more metallic motifs for functional purposes, such as forming in particular one or more conductive metallic printed circuit tracks, one or more. sensor / detector electrodes or one or more radio frequency antennas.

[0034] According to another variant (hereinafter, “V2 variant”), thermoforming step C is carried out after metallization step D. According to this V2 variant, step C is therefore a thermoforming step of the metallized flat substrate, during which the flat substrate and the metal deposit formed on its surface undergo simultaneous deformation. While it is possible (“V2a variant”) for the temporary masking coating to be present on the surface of the flat substrate during thermoforming step C, this is not strictly necessary. On the contrary, it is advantageous for the removal of the temporary masking coating step E in this V2 variant to be carried out before thermoforming step C (“V2b variant”), so as to prevent deformation of the temporary masking coating from potentially damaging the metal deposit.

[0035] According to this variant V2, step B, the formation of the temporary masking coating, and step D, the metallization, are both carried out on the flat substrate. This simplifies the implementation of steps B and D, as they can easily be performed inline in an industrial setting. However, it is preferable to reserve this variant V2 for the manufacture of three-dimensional articles requiring limited deformation of the metallized substrate during step C, the thermoforming step, in order to limit the risk of degradation in the quality of the metal deposit during thermoforming, which could lead to breakage or inhomogeneity of the conductive properties of the metal pattern(s), and / or for the manufacture of three-dimensional articles whose metal pattern(s) is / are essentially decorative.

[0036] Performed after step B, metallization step D (hereinafter abbreviated as "step D") consists of forming on the surface of the substrate, and at least on the area(s) not masked by the temporary masking coating or on one or more areas of the substrate corresponding to the area(s) not masked by the temporary masking coating, a metallic deposit intended to form all or part (i.e., alone or possibly in combination with a complementary metallic deposit, for example) of the desired metallic pattern(s). "Metallic deposit" here generally means a deposit, a layer, comprising—or formed of—at least one metal or metallic substance, including at least one elemental metal (or "elemental element"), at least one mixture of elemental metals, at least one metallic alloy, and / or at least one metallic oxide.

[0037] Advantageously, the metallization step D is carried out such that the metallic deposit obtained at the end of this step comprises at least one metal (or "metallic substance") chosen from the group comprising: an elemental metal such as silver Ag, gold Au, nickel Ni, copper Cu, iron Fe, tin Sn, cobalt Co, an alloy of these, a mixture of two or more of these elemental metals, or one or more oxides of at least one of these elemental metals.

[0038] Advantageously, particularly with regard to the electrical conductivity properties and / or the decorative properties (e.g., the "mirror" effect) of the metallic pattern(s), the metallization step D is carried out in such a way that the metallic deposit is solid metal, optionally loaded with additional particles (or "fillers") which may be organic or inorganic. In this case, the metallic deposit is therefore essentially—if not entirely, apart from the inevitable non-metallic impurities—composed of metal (or "metallic substance"), as defined above. Advantageously, the solid metal may consist of a single pure elemental metal (typically more than 90%, preferably more than 95%, and even more preferably more than 98%).For example, the metallic deposit could thus be formed from a pure elemental metal, for example pure silver (Ag) (preferably more than 95%, and even more preferably more than 98%), and possibly additional particles. If applicable, the bulk metal forms a bulk matrix within which the additional particles are dispersed. These additional particles are preferably chosen to have a characteristic size of less than 100 µm. Generally, the use of such additional particles aims to modify the physical (e.g., mechanical / tribological, electrical, and / or optical) and / or intrinsic chemical properties of the bulk metal with which they are deposited.As non-limiting examples of additional particles that may be included, alone or in mixtures, in a bulk metal deposit, we may mention: diamond carbon particles, silicon carbide particles SiC, molybdenum disulfide particles MoS2, particles of one or more rare earths or rare earth oxide(s), graphene particles, particles of a fluoropolymer (such as polytetrafluoroethylene (PTFE), for example), particles of elemental metal or metal oxide(s), etc.

[0039] The metallic deposit can be single-layer or multi-layer, depending on the desired properties and the intended applications of the metallic pattern(s). Advantageously, step D is carried out such that the metallic deposit, after said metallization step D, has a thickness between 10 nm and 5 pm, preferably between 10 nm and 1 pm, and even more preferably between 10 nm and 500 nm. According to an alternative, step D is carried out such that the thickness of the metallic deposit obtained after step D is substantially constant throughout the entire extent of said metallic deposit, that is to say, the thickness is substantially identical at every point of the metallic deposit. It is thus possible to obtain one or more metallic patterns that have a substantially constant thickness. The entire extent of the metallic pattern(s). According to another variant, step D is carried out in such a way that the thickness of the metallic deposit obtained at the end of step D varies according to the extent of said metallic deposit (while preferably remaining within the aforementioned ranges of values), that is to say, the metallic deposit has at least a first and a second distinct zone, the thickness of the metallic deposit being either increasing or, conversely, decreasing (thickness gradient) from said first zone to said second zone. Such a variation in the thickness of the metallic deposit thus advantageously makes it possible to obtain one or more metallic patterns that define zones of different electrical conductivity or resistivity, or even of different transparency or reflectivity to electromagnetic waves (for example, to visible, IR or UV light, to radio frequency waves, etc.).), which may be of particular interest depending on the intended functional and / or decorative applications.

[0040] Various metallization methods, and in particular various so-called "wet" or "dry" methods, can be considered for carrying out step D of the metallization process. Among the main "dry" methods considered here are physical vapor deposition (PVD) and chemical vapor deposition (PVD). However, these techniques have a major drawback: the substrate must be placed under vacuum to perform the metallization.It is therefore preferable that the metallization step D implement one or more so-called "wet" metallization methods, electrolytic or chemical (non-electrolytic), using one or more suitable metallization solutions, which are generally easier and less expensive to implement, particularly in an industrial manufacturing context.

[0041] Thus, according to an advantageous embodiment, the metallization step D is carried out by non-electrolytic (chemical) deposition from one or more metallization solutions (or "redox solution(s)"), advantageously containing at least one metal in the form of a metal cation (i.e., metal in cationic form, forming an oxidant) and at least one reducing agent capable of transforming the metal cation into a metal. Said at least one metal cation can advantageously be obtained by dissolving at least one corresponding metal salt in the liquid phase.

[0042] According to a first embodiment of this non-electrolytic variant, the aforementioned non-electrolytic deposition (or "metallization") is more specifically carried out by spraying the metallization solution(s) in the form of one or more aerosols. In this case, the process according to the invention optionally includes, before said metallization step D, at least one of the following additional steps: - a step P for increasing the surface energy of the substrate, knowing that in the case where the process includes an activation step H, such a step P for increasing the surface energy of the substrate may possibly be provided before said activation step H; - a step Q of wetting the surface of the substrate; - a step R of rinsing the surface of the substrate.

[0043] Step P of processing to increase the surface energy of the substrate can possibly be considered as a step F of preparing the surface of the substrate.

[0044] This embodiment using aerosol spraying is particularly advantageous because, in addition to the excellent properties of the metallic deposit that can be formed in this way, it allows for simple and rapid metallization of substrates of all sizes, and in particular of large substrates. Furthermore, it is particularly well-suited to cases where the metallization step D is carried out after the thermoforming step C, and where the surface to be metallized is therefore not flat but rather deformed. Moreover, this embodiment makes it particularly easy to obtain a metallic deposit whose thickness varies according to the extent of said metallic deposit, as described above.

[0045] According to a second embodiment of this non-electrolytic variant, the aforementioned non-electrolytic deposition is a self-catalytic (or "electroless") chemical deposition (or "metallization") carried out by immersing the substrate in one or more metallization solutions, optionally comprising, in addition to one or more metal cations and one or more reducing agents, one or more complexing agents, one or more stabilizing agents, and other possible additives (surfactants, etc.). In this case, the process advantageously includes a step H for activating the substrate surface prior to the metallization step D, and optionally, before said activation step H, at least one of the following steps, preferably in the following order: - satin finishing step S, preferably implemented between step B of temporary masking coating formation and step H of activation; - step T of rinsing the surface of the substrate, in the event of implementation of such a step S of satin finishing.

[0046] According to another wet-process variant, the metallization step D can optionally be carried out by electrolytic deposition (or "electrodescoping" or "galvanosteping"). Such electrolytic deposition (or "metallization") is based on a redox reaction using an electric current, starting from a metallization solution typically containing at least one metal in cationic form in an aqueous medium. An electric current is applied between the substrate to be metallized and a counter electrode. The metal cation is then reduced to the surface of the substrate to form a metallic deposit. However, such a metallization method by electrolytic deposition is less preferable than the two previous ones insofar as it is only conceivable in the single case where the thermoformable material of the substrate is (electro)conductive, which therefore strongly limits the choice of thermoformable material, excluding in particular most thermoformable polymer materials.

[0047] Optionally, the metallization step D can be carried out on the one hand according to the first embodiment of the above-mentioned non-electrolytic metallization variant (i.e. by spraying aerosol(s)) and optionally, on the other hand, according to the second embodiment of the above-mentioned non-electrolytic metallization variant (i.e. by immersion) and / or according to the above-mentioned electrolytic deposition variant.

[0048] As can be seen from the above, step E of removal of the temporary masking coating (hereinafter abbreviated as "step E") aims to remove the temporary masking coating present on the surface of the substrate.

[0049] As such, step E can be carried out: - either before the metallization step D, in particular in the case where the process includes a step H of activation of the surface of the substrate prior to the metallization step D and where the temporary masking coating is intended to allow selective activation of the surface of the substrate; - either after the metallization step D; - either, more preferably, during the metallization step D, or partly during the metallization step D and partly after the metallization step D, or partly before the metallization step D, partly during the metallization step D and partly after the metallization step D.

[0050] Carrying out step E at least partially concurrently with carrying out step D of metallization, as preferably proposed above, advantageously contributes to accelerating and simplifying the implementation of the process according to the invention, by limiting the number of successive steps required.

[0051] Advantageously, step E of removing the temporary masking coating is carried out at least partially by chemical, non-mechanical means in order to remove said temporary masking coating in a simple and clean manner from the surface of the substrate, in particular in the case where said step E is carried out after step C of thermoforming, limiting the risk of degrading the fineness and precision of the metallic pattern(s) that one seeks to obtain.

[0052] In this respect, step E of removing the temporary masking coating advantageously includes at least one operation of dissolving (at least partially) the temporary masking coating by at least one solvent used in the process. Optionally, step E may even advantageously consist of Specifically, the temporary masking coating is dissolved (at least partially) by at least one solvent used in the process. "Dissolution by at least one solvent" here refers to the disintegration, breakdown, or loss of cohesion, total or partial, of the temporary masking coating under the action of a specific fluid (preferably a liquid) chosen for its specific chemical aggressiveness towards the temporary masking coating, such as to allow its disintegration, detachment, and removal from the substrate surface. This may be a dissolution mechanism in a solvent in the strict chemical sense, but not necessarily. Preferably, the temporary masking coating is alkali-soluble (or at least alkali-sensitive) so that it can be preferentially dissolved by an alkaline solvent used in the process.

[0053] Step E may optionally include, prior to the dissolution of the temporary masking coating, an exposure operation under actinic radiation (e.g., under UV light) and / or a heat treatment operation of the temporary masking coating, in order to weaken the temporary masking coating and / or facilitate its subsequent dissolution. Step E may optionally include, after such a dissolution operation, a liquid-phase entrainment operation and / or a mechanical entrainment operation by a gas (preferably air), in particular to facilitate the removal of the dissolved temporary masking coating and / or any debris not fully dissolved therefrom.

[0054] In the case mentioned above where step E is carried out during metallization step D, or partly during and partly after metallization step D, or partly before, partly during, and partly after metallization step D, the solvent used to remove the temporary masking coating by dissolution is preferably at least contained in the metallization solution(s) used during step D. This therefore involves dissolving the temporary masking coating with at least one solvent used during step D. The time required for the formation of the metallic deposit during said metallization step D is then preferably chosen to be less than or equal to the time required for the temporary masking coating to dissolve under the action of said solvent.

[0055] In addition or alternatively, the process may include a step I of rinsing the surface of the metallized substrate and the solvent enabling the removal by dissolution of the temporary masking coating may be contained in a rinsing liquid implemented in said step I.

[0056] However, it remains possible, although less preferable, that step E could be carried out by a non-chemical method, for example by ablation at laser, using a jet of pressurized gas, or by any suitable known mechanical means.

[0057] Having stated this, certain aspects of the aforementioned steps will be described in more detail below.

[0058] - Step A of supplying a flat substrate made of thermoformable material -

[0059] Although the implementation of a flat glass (mineral) substrate could be envisaged While the substrate may be made of metal, it is preferable for the flat material to be thermoformable (thermoplastic), whether filled or unfilled, or a thermoformable polymer matrix composite. Indeed, thermoformable polymer or polymer matrix materials are generally easier to process due to a softening temperature significantly lower than that of glass or most metals. Among the thermoformable polymer materials that can be considered, non-limiting examples include polystyrene (PS), high-impact polystyrene (SB / HIPS), polyethylene (PE), polypropylene (PP), polycarbonate (PC), acrylonitrile butadiene styrene (ABS), polyvinyl chloride (PVC), polymethyl methacrylate (PMMA), and thermoplastic polyesters such as polylactic acid (PLA), polyethylene terephthalate (PET), and glycolized polyethylene terephthalate (PETG).In the case where the flat substrate is a thermoformable composite material with a polymer matrix, the polymer(s) of the polymer matrix can be chosen, for example, from the thermoformable polymer materials listed above.

[0060] More generally, the thermoformable material of the flat substrate can be a single material or, conversely, a composite material. The flat substrate can be single-layered or possibly multi-layered.

[0061] Advantageously, said flat substrate may be a film, a sheet or a plate of a thermoformable polymer material or of a thermoformable composite material with a polymer matrix, of a thickness of between 8 pm and 15 mm, and preferably even more of between 25 pm and 10 mm, which facilitates its handling and subsequent thermoforming.

[0062] Depending on the material and thickness chosen, the flat substrate can be substantially rigid or, conversely, flexible. However, in practice, particularly to facilitate industrial implementation of the process, it is preferable for the flat substrate to be flexible, meaning that it can advantageously be curved or folded by human force alone without breaking, deforming, or degrading irreversibly. The flat substrate can thus, for example, advantageously be supplied continuously from a coil of wound substrate and then rewound into a coil after step B of the temporary masking coating formation or after step D of metallization, in the case (variant V2) where the latter is carried out before step C of Thermoforming (a process known as "roll-to-roll" or "R2R" in English). In contrast, a "rigid substrate" is defined as a substrate that cannot be curved or bent by human force alone without breaking or deteriorating irreversibly.

[0063] - Step F of substrate surface preparation -

[0064] As previously introduced, the process may include one (or more) step(s) F for preparing the substrate surface, which aims to modify certain properties of the substrate surface in preparation for one (or more) subsequent step(s) of the process. This may involve one (or more) step(s) for preparing the surface of the flat substrate, carried out before the thermoforming step D, and / or one (or more) step(s) for preparing the surface of the thermoformed substrate, carried out after the thermoforming step C.

[0065] Furthermore, such a step F can be carried out before or after step B of forming the temporary masking coating. In some cases, preparing the surface of the flat substrate before the formation of the temporary masking coating prevents physicochemical changes to the temporary masking coating, which could lead to excessive adhesion of the latter to the surface of the flat substrate, potentially making its subsequent removal more difficult. In other cases, preparing the surface of the flat substrate can be carried out after the formation of the temporary masking coating, so as to strengthen the cohesion and adhesion of the temporary masking coating and, possibly, slow its removal.

[0066] Step F may include a cleaning and / or degreasing operation of the substrate surface, using any products known and suitable per se. In addition to or instead of such a cleaning / degreasing operation, step F may include a deposition operation of a varnish, optionally colored / pigmented, for example a UV-curing varnish applied by spraying, onto the substrate surface by any known and suitable means such as a compressed air paint gun (for example, a High Volume Low Pressure (HVLP) spray gun).

[0067] Optionally, step F may include at least, or correspond to, a surface energy increase treatment of the substrate (step P).

[0068] - Step B of the formation of the temporary masking coating -

[0069] The practical modalities for carrying out step B may depend in particular on the nature of the thermoformable material of the flat substrate, the precision required for the definition of the unmasked area(s), and possibly, in the case in particular of the Via sub-variant mentioned above, on the conditions of the thermoforming step C (in particular in terms of temperature and deformation rate). to which we later wish to subject the flat substrate and the temporary masking coating during step C of thermoforming.

[0070] Said step B of formation of the temporary masking coating is preferably carried out by - selective deposition of a layer of a liquid or paste-like masking composition onto the surface of the flat substrate, by any known and suitable application technique, and for example by screen printing, pad printing, flexography, gravure printing and / or direct printing (for example, by drop-by-drop or "inkjet"), - possibly followed by drying and / or hardening of the layer of masking composition thus deposited.

[0071] Depending on the formulation of the chosen masking composition, its drying and / or hardening may involve drying / desolvation, possibly under the effect of heat, or polymerization / crosslinking of the deposited masking composition under the effect of heat and / or under the action of actinic radiation (for example, by exposure to ultraviolet (UV) light). Such drying and / or hardening of the deposited masking composition layer proves particularly advantageous depending on the fluidity of the masking composition, in order to prevent uncontrolled spreading of the masking composition that would impair the definition of the shape of the unmasked area(s).

[0072] Alternatively, although in a more complex and therefore less preferential way, step B can be carried out by - (non-selective) deposition of said liquid or paste masking composition onto the surface of the flat substrate, for example by dipping, spraying, or any other known and suitable non-selective deposition technique, - possibly followed by drying and / or hardening of the masking composition layer thus deposited, - followed by selective removal of the temporary masking coating formed to locally create one (or more) unmasked area(s) on the surface of the flat substrate.

[0073] Optionally, said masking composition is deposited on the surface of the flat substrate during step B according to a two-dimensional masking pattern previously defined during a step G as described below.

[0074] The masking composition can be chosen to be substantially colorless, or conversely, colored / pigmented. A masking composition containing a dye / pigment allows, where appropriate, for easier visualization of the temporary protective coating formed on the surface of the flat substrate, which can prove useful in certain cases.

[0075] Preferably, step B is carried out so that the temporary masking coating, at the end of step B (and therefore, where applicable, after drying and / or hardening of the deposited masking composition layer), has a thickness of between 100 nm and 50 pm, preferably between 500 nm and 20 pm, and even more preferably between 1 pm and 10 pm. Such a thickness provides a sufficient barrier effect on the surface of the substrate areas not intended to subsequently bear the metallic pattern(s). Moreover, such a thickness advantageously contributes to the ability of the temporary masking coating to undergo thermoforming step C without significant damage, where applicable (Via variant).According to one variant, step B is carried out such that, at the end of step B, the thickness of the temporary masking coating is substantially constant throughout its entire extent; that is, its thickness is substantially identical at every point of said temporary masking coating. According to another variant, step B is carried out such that, at the end of step B, the thickness of the temporary masking coating varies according to its extent (while preferably remaining within the aforementioned ranges of values); that is, the temporary masking coating has at least a first and a second distinct portion, the thickness of the first portion being different from the thickness of the second portion.Such a difference in the thickness of the temporary masking coating, preferably within the ranges of values ​​indicated previously, can prove to be of interest, particularly in the case of variant VI, to locally adapt the thickness of the temporary masking coating to the amplitude of the deformation to which a given area of ​​the (masked) substrate is to be subjected during step C of thermoforming.

[0076] It should be noted that, since step B of forming the temporary masking coating is carried out on the (flat) substrate before step C of thermoforming, the temporary masking coating does not, at the end of step B, form, or at least not necessarily, an exact negative of the metallic pattern(s) that one seeks to obtain ultimately on the surface of the thermoformed substrate. Indeed, according to the sub-variant Via described above, the temporary masking coating itself undergoes deformation during step C, so that it is the deformed temporary masking coating, obtained at the end of step C, that advantageously corresponds to the negative of the metallic pattern(s) to be obtained. According to variant V2, the temporary masking coating may or may not be present on the surface of the substrate during the execution of step C of thermoforming.In the preferential case where step E of removing the temporary masking coating is carried out before step C, the surface of the flat substrate is therefore provided with a (or . several) "raw" metallic pattern(s) which will undergo deformation during thermoforming step C to obtain the desired metallic pattern(s). Thus, the temporary masking coating corresponds in this case to the negative of said "raw" metallic pattern(s).

[0077] As mentioned previously, in the case of sub-variant Via of variant VI, the temporary masking coating is advantageously thermoformable and designed, particularly in terms of its elongation / deformation capacity without breakage and temperature resistance, to withstand the conditions of thermoforming step C of the flat substrate without significant degradation of its surface masking function. Typically, the temporary masking coating is advantageously designed so that, particularly at the forming temperature chosen for thermoforming step C, it exhibits an elongation / deformation rate without breakage at least equal to the deformation rate desired for the flat substrate during the thermoforming step.

[0078] Such a particular design can typically involve an appropriate choice of masking composition formulation, it being understood that the exact formulation of the masking composition may depend in practice on a number of factors such as, in particular, the method of application of the masking composition to the substrate, the nature of the thermoformable material of the substrate, the forming temperature at which thermoforming step C is carried out, the thickness of the temporary masking coating to be formed, the rate of deformation that is desired to be imparted to the flat substrate and the temporary masking coating during thermoforming step C, etc.For example, such an ability of the temporary masking coating to withstand the conditions of the execution of step C of thermoforming the flat substrate can be conferred to it by a choice, in the formulation of the masking composition, of a particular organic polymeric binder capable of forming an organic polymeric matrix possessing the desired elongation / deformation without breakage and temperature resistance capacities.

[0079] The preferentially soluble (or sensitive) character of the temporary masking coating to a solvent used in the process, and more preferably at least to a solvent contained in the or one of the metallization solutions used in step D, can be conferred to the temporary masking coating by a choice in the formulation of the masking composition, and for example by choosing a component, such as in particular a polymeric organic binder intended to form a polymeric organic matrix, which is soluble by the solvent in question, or at least sensitive to the latter.

[0080] For example, the masking composition implemented during step B may include all or part of the following components (it being understood that the content of the The masking composition in each of these components may depend in particular on the chosen application method of said masking composition, as well as its possible drying / hardening method): - a carrier component, which may represent between 20% and 70% of the total weight of the masking composition. The carrier component may comprise an organic or aqueous solvent, a monomer, an oligomer, or a mixture of these compounds. Its function is to solubilize or suspend the remaining components described below. The carrier component contributes to the viscosity and rheological properties of the masking composition, thus facilitating its application. It is intended to evaporate in the case of a thermally curing masking composition and / or to be crosslinked in the case of a UV-curing masking composition, for example; - A binding component, which can represent 30% to 70% of the total weight of the masking composition. It is advantageously designed to form an organic polymer matrix, which can be acrylic, polyester, vinyl, styrene, or polyamide in the case of a heat-curing masking composition. In the case of a UV-curing masking composition, the binding component can be a mixture of monomers and oligomers of the acrylate, cationic, or anionic type, as well as the polymers mentioned above. The binding component may also act as a carrier.The binding component provides the temporary masking coating with its main properties, including its adhesion to the substrate, its resistance to friction, its possible sensitivity to a solvent used in the process (for example, alkali sensitivity) and its possible ability to withstand step C of thermoforming and to thermodeform without breaking during the latter; . - a solid component, organic or inorganic, which may represent between 1% and 50% of the total weight of the masking composition. It may correspond to a mineral or organic filler, possibly fibrous. It may impart, or contribute to imparting, to the masking composition and / or the temporary masking coating a color, particular rheological properties and resistance to friction; - One or more additives, representing between 0.01% and 10% of the total weight of the formula. These may include one or more rheology additives, wetting agents, antifoaming agents, dispersants, surfactants, stabilizers, or colorants. These additives allow, among other things, for adjusting the rheology, applicability, and wettability of the masking composition on the substrate; accelerating or slowing down the drying or hardening of the masking composition; improving the dispersion and stabilization of the solid component; coloring the masking composition; or other enhancements. certain properties of the temporary masking coating such as its resistance or gloss; - Optionally, one or more photoinitiators, representing between 5% and 15% of the total weight of the masking composition. In the case of a UV-curable masking composition, they enable the crosslinking of monomers and oligomers. They can be radical, cationic, or anionic in nature.

[0081] By way of non-limiting examples of carrier components, we can mention: water, butanol, methoxypropanol, ethyl acetate, butyl acetate, cyclohexane, 2-butoxyethanol acetate, 2-methoxy-l-methylethyl acetate, propylene carbonate, isopropyl myristate, diethylene glycol monoethyl ether acetate, glycerol, hexane, methylcyclohexane, or, among the monomers: PETIA, HDDA, IBOA, TMPTA, TPGDA, HEMA, etc. Non-limiting examples of binding components include: vinyl acetate and vinyl chloride copolymer, acrylic resin, polyvinyl alcohol, polyvinylpyrrolidone, polyurethane, aliphatic urethane acrylate, polyester acrylate, polyester, etc. Non-limiting examples of solid components include: silica, barium carbonate, barium sulfate, aluminum hydroxide, wax, etc.

[0082] - Step G of defining a two-dimensional masking pattern -

[0083] It may prove important, particularly when said at least one metallic motif is intended to play a functional role, and especially for (radio-)electrical or electronic applications, to ensure perfect control of the shape of the metallic motif obtained on the surface of the thermoformed substrate. In this respect, the process according to the invention may advantageously include, prior to step B, a step G for defining a two-dimensional masking motif, according to which the temporary masking coating is then formed on the surface of the flat substrate during said step B of forming the temporary masking coating, based on a model of a deformation of the flat substrate, and, where applicable, of the temporary masking coating, during step C of thermoforming and a representation (or model) of said at least one metallic motif to be obtained.In other words, a two-dimensional masking pattern is defined by "inverse anamorphosis," such that this two-dimensional masking pattern, according to which the temporary masking coating is formed on the surface of the flat substrate during step B, allows the desired metallic pattern(s) to be obtained by anticipating and compensating for the effects of the deformation caused by thermoforming step C. The step of defining such a two-dimensional masking pattern can be carried out using commercially available computer software, such as [software name missing]. Examples include the T-SIM® software from SIMCON (formerly CADFLOW), the PAM-FORM™ software from ESI GROUP, the ANAMAP™ software solution from KALLISTO, and the Thermo 3D™ software from QUADRAXIS.

[0084] - Step H of substrate surface activation -

[0085] Depending on the nature of the substrate, the nature of the metallic deposit to be formed, and depending on the one or more metallization method(s) used for the metallization step D, a prior activation step of the substrate surface may prove necessary to allow, or at least to facilitate, the formation of the metallic deposit on the substrate surface.

[0086] In the case where the metallization step D is carried out by non-electrolytic deposition by spraying one (or more) metallization solution(s) in aerosol form, such an activation step H (or at least a "sensitization" step) may be necessary for the deposition of certain metals. Its purpose is, in particular, to accelerate the redox reaction occurring in step D. During step H, the substrate surface is brought into contact with at least one sensitizing chemical species, which adsorbs onto the substrate surface and thus accelerates the metallization reaction.

[0087] Preferably, the activation step H is carried out after the temporary masking coating formation step B and before the removal step E, so that the sensitizing chemical species (or species) adsorb(s) both onto the temporary masking coating and onto the unmasked area(s), i.e. not covered by the latter.

[0088] In practice, step H is preferably carried out by spraying at least one sensitizing solution onto the surface of the substrate, using any known and suitable means, such as, for example, a compressed air paint gun (e.g., a High Volume Low Pressure (HVLP) spray gun). Alternatively, step H could be carried out by immersing the substrate in at least one sensitizing solution.

[0089] For example, a first sensitizing solution based on stannous chloride (SnCl2) or SnSO4 / H2SO4 / quinol / alcohol is applied by spraying or immersion. A palladium or silver-based solution capable of reacting with Sn2+ ions to form nucleation centers on the substrate surface is then deposited in the same way, or a colloidal PdSn solution formed ex situ. For more details, see, for example, "Metal Finishing Guidebook and Directory Issue," 1996, Metal Finishing publication, pages 354, 356, and 357; H. Narcus, "Metallizing of Plastics," Reinhold Publishing Corporation, 1960, Chapter 2, page 21; F. Lowenheim, or "Modern Electroplating," John Wiley & Sons publication, 1974, Chapter 28, page 636. Advantageously, the sensitization of the The substrate surface is activated using a stannous chloride-based sensitizing solution, for example, according to the implementation method described in document FR-2 763 962 Bl. In this case, a rinsing step using a rinsing liquid as described below is carried out immediately after sensitization, without an intermediate step. Alternatively, the substrate surface is activated using a sensitizing solution, in particular palladium chloride, for example, according to the implementation method described in document FR-2 763 962 Bl. In this case, a rinsing step using a rinsing liquid as described in the examples below is carried out immediately after the activation step H, without an intermediate step.

[0090] In the case where the metallization step D is carried out by autocatalytic (“electroless”) chemical deposition by immersion in one or more metallization solutions, such an activation step H, which advantageously aims to accelerate the catalytic redox reaction occurring in step D, is generally indispensable. It consists of depositing a current-free chemical metallization catalyst, for example an Sn / Pd type catalyst, onto the surface of the masked substrate.

[0091] Preferably, the activation step H is carried out after the temporary masking coating formation step B and before the removal step E, so that the catalyst is adsorbed both on the temporary masking coating and on the unmasked area(s), i.e. not covered by the latter.

[0092] Step H is preferably preceded by a satin finishing step S followed by a rinsing step T. Step S corresponds to a treatment that increases the surface energy of the substrate and / or increases the roughness of the substrate, which may be of the type defined below for step P. In the case of autocatalytic chemical deposition, satin finishing is preferably achieved by physical treatment (corona discharge, plasma treatment, etc.) or chemical treatment (for example, a sulfo-chromic or other treatment) in order to provide sufficient adhesion to the metal deposit to be formed. The rinsing step T advantageously corresponds to a rinsing of the type defined below for step R.

[0093] - Step C of thermoforming the flat substrate -

[0094] Step C of thermoforming the flat substrate can advantageously be carried out by any known means and thermoforming technique, adapted of course to the characteristics of the substrate (nature of the thermoformable material, thickness of the flat substrate, etc.) and, where appropriate, to the intrinsic characteristics of the temporary masking coating and / or to the intrinsic characteristics of the metallic deposit or of the metallic pattern(s) possibly present on the surface of the flat substrate to be thermoformed.

[0095] Typically, step C is carried out by heating the flat substrate in an advantageous manner The material is heated homogeneously, by conduction and / or convection and / or radiation, until the thermoformable material of the flat substrate reaches a forming temperature sufficient to make the flat substrate malleable. The forming temperature in question can obviously vary depending on the thermoformable material chosen. For a thermoformable polymer material, the forming temperature is typically chosen to be at least equal to the glass transition temperature of the material in question, and advantageously lower than the melting temperature of the material. Once made malleable, the flat substrate is pressed against a male (positive mold) or female (negative mold) mold (or counterform), advantageously with vacuum and / or pressure suction, so that the flat substrate deforms and conforms to the shape of the mold.The deformed substrate is then cooled so that the thermoformable material hardens and retains the shape imparted by the mold, and then the deformed substrate is removed from the mold.

[0096] - Metallization step D -

[0097] As introduced previously, the metallization step D can be carried out after the thermoforming step C (variant VI) or, on the contrary, before the thermoforming step C (variant V2).

[0098] — Non-electrolytic deposition by spraying in aerosol form(s)

[0099] Step P, for increasing the surface energy of the substrate, step Q, for wetting the substrate surface, and step R, for rinsing the substrate surface, which may optionally precede step H, for activation, or step D, for metallization, are described below, as a preamble to a description of step D, the metallization, according to the embodiment envisaged above, in which the metallization is carried out by non-electrolytic (chemical) deposition by spraying one (or more) metallization solution(s) in aerosol form. In the case where step D is carried out after step C, the thermoforming (variant VI), said steps P, Q, and R are preferably carried out after said step C.

[0100] Step P of the surface energy increase treatment of the substrate can be carried out: - by physical treatment, preferably chosen from the following physical treatments: flame treatment, plasma treatment, corona treatment, increased roughness (by sandblasting, shot blasting, etc.) and combinations thereof, and / or - by chemical treatment, preferably chosen from the following chemical treatments: application of a silane-based solution, depassivation of the surface using one or more acidic solutions, polishing with rare earth oxide, fluorination, acid or alkaline chemical attack to create micro-roughness and their combinations.

[0101] More preferably, the physical treatment is a flame treatment and / or Plasma treatment is used, particularly when the substrate, whether flexible or rigid, is made of a thermoformable polymer or a thermoformable composite material with a polymer matrix. Flame treatment involves, for example, passing the substrate to be metallized through a flame with a temperature ranging from 1200°C to 1700°C. The flame treatment typically lasts from 4 to 50 seconds. The flame is preferably produced by burning a fuel, such as propane, in the presence of an oxidizer like oxygen. Plasma treatment involves, for example, passing the substrate to be metallized through a plasma torch, such as those marketed by ACCYS® or PLASMATREAT®. More preferably, chemical treatment is fluorination, when the substrate, whether flexible or rigid, is made of a thermoformable polymer or a thermoformable composite material with a polymer matrix.Fluoridation, for example, involves bringing the substrate to be metallized into contact, within a reduced-pressure chamber, with a gaseous solution based on an inert gas (argon) containing a fluorine additive. Such fluoridation can be carried out, for example, with equipment of the type marketed by AIR LIQUIDE®.

[0102] In any event, these physical and / or chemical treatments for increasing the surface energy of the substrate must advantageously be carried out so that the surface energy of the substrate is, at the end of step P, greater than or equal to 50 or 55 dynes, preferably greater than or equal to 60 or 65 dynes, and even more preferably greater than or equal to 70 dynes. Below these values, the substrate wetting could prove insufficient and the metallic deposit obtained after metallization could exhibit unsatisfactory adhesion, gloss, and reflectivity characteristics. The surface energy value can be measured, for example, by techniques known to those skilled in the art, consisting of applying a specific solution to the substrate with a brush or felt-tip pen and measuring the shrinkage time of the solution thus applied.

[0103] The wetting step Q typically consists of coating the substrate surface with a liquid film, for example by spraying or by vaporizing / condensing a wetting liquid, to promote the spreading of the metallizing solution(s) ("redox solution(s)"). The wetting liquid is preferably chosen from the following group: deionized or non-deionized water, optionally with one or more anionic, cationic, or neutral surfactants; an alcoholic solution comprising one or more alcohols (for example, isopropanol, ethanol, and mixtures thereof); and mixtures thereof. For example, deionized water with an added anionic surfactant and ethanol could be chosen as a wetting liquid. In a wetting variant in which the wetting liquid is transformed into vapor, which is then sprayed onto the substrate where the vapor condenses, it is preferable The liquid should be essentially aqueous for obvious reasons of industrial convenience. The wetting time depends on the surface area of ​​the substrate and the spray or vaporization / condensation rate of the wetting liquid. The wetting step Q can possibly replace the activation step H.

[0104] Advantageously, the rinsing step R, as well as the other rinsing steps which punctuate the process, like step I or step T, consist of bringing all or part of the surface of the substrate into contact with one or more rinsing liquid(s), preferably demineralized water, by projecting an aerosol of the rinsing liquid(s).

[0105] Step D of non-electrolytic (chemical) metallization by projection of one (or more) metallization solution(s) in aerosol form(s) advantageously relates to the process described in documents FR-2 763 962 Bl, EP-2 326 747 Bl or EP-2 318 564 B1.

[0106] The metallization step D is advantageously carried out (at least) by non-electrolytic deposition from: - either a single metallization solution containing said at least one metal in the form of a metallic cation and said at least one reducing agent capable of transforming the metallic cation into metal, - either two distinct solutions: the first solution (“oxidizing solution”) containing at least one metal in the form of a metallic cation (oxidant(s)) and the second solution (“reducing solution”) containing one or more reducing agent(s), - or even a plurality of distinct solutions, each of which may contain either at least one metal in the form of a metallic cation (oxidant(s)), or one or more reductant(s), provided that at least one of the solutions (“oxidizing solution”) contains at least one metal in the form of a metallic cation and that at least one other of the solutions (“reducing solution”) contains one or more reductant(s).

[0107] The reducing agent is advantageously chosen to be sufficiently strong to reduce the metal cation to metal, i.e., the standard redox potential of the oxidizing / reducing couple of the chosen reducing agent is lower than that of the oxidizing / reducing couple of the oxidant (gamma rule). Such a non-electrolytic variant is particularly advantageous in that it allows the formation, on the surface of a substrate that is indifferently conductive or non-conductive, of a massive metal deposit, as envisaged above, and moreover, with a thickness advantageously within the ranges of values ​​mentioned above.

[0108] During the metallization step D, the metallization solution(s) is / are sprayed in the form of one or more aerosols onto the masked substrate, and in particular at least onto the unmasked area(s) thereof. "Aerosol" here means a collection of fine particles of the metallization solution(s). suspended in a gaseous medium (for example, air). It can thus advantageously be a mist of droplets smaller than 100 pm, preferably smaller than 60 pm, and even more preferably from 0.1 pm to 50 pm, obtained by nebulization and / or atomization of the metallization solution(s).

[0109] Advantageously, the metallization solution(s) (“redox solution(s)”) can be obtained from solutions, advantageously aqueous, of one or more oxidizing metal cations (typically obtained by dissolving one or more corresponding metal salts) and one or more reducing compounds, preferably by diluting concentrated stock solutions, the diluent preferably being demineralized water. Depending on the nature of the metal deposit to be formed, the spraying of the metal solution(s) can be carried out continuously, i.e., in a single step, or discontinuously by alternating spraying phases and relaxation times. For example, for a silver-based metal deposit, the spraying will preferably be carried out continuously.For example, for a nickel-based metal deposit, the spraying will preferably be carried out discontinuously by alternating spraying phases and relaxation times. Depending on the desired thickness of the metal deposit, the spraying time can advantageously vary from 0.5 s to 200 s, preferably from 1 s to 50 s, and even more preferably from 2 s to 30 s for a substrate surface area of ​​1 dm². Modulating the spray cone allows the metallizing solution(s) to be sprayed over a more or less wide area of ​​the substrate. By modulating the spraying time and / or the amount of metallizing solution(s) sprayed locally, it is possible to obtain a gradient of metal deposit thickness, as mentioned previously.

[0110] The application of the metallizing solution(s) can be carried out using any suitable spraying means, preferably using one or more compressed air paint guns, such as, for example, one or more high-volume, low-pressure (HVLP) guns. Advantageously, the spraying means and the substrate can be set in relative motion (translation and / or rotation) to allow for in-line metallization and / or to ensure good coverage of all areas of the substrate to be metallized, particularly in cases where the latter has been thermoformed prior to the metallization step D.

[0111] According to a first projection method, one or more solutions of metal cation(s) ("oxidizing solution(s)") and one or more solutions of reducing agent(s) ("reducing solution(s)") are simultaneously and continuously projected onto the surface to be treated, in the form of one or more aerosols. In this case, the mixing between the oxidizing solution and the reducing solution can take place just before the formation of the aerosol or by melting an aerosol produced at The spraying method begins with the oxidizing solution and an aerosol produced from the reducing solution, preferably before contact with the surface of the substrate to be metallized. A second spraying method involves successively spraying, via one or more aerosols, one or more solutions of metal cation(s) ("oxidizing solution(s)") followed by one or more solutions of reducing agent(s) ("reducing solution(s)"). In other words, the redox solution is sprayed by separate application(s) of one or more solutions of one or more metal oxidants and one or more solutions of one or more reducing agents. This second option corresponds to an alternating application of the reducing solution(s) and the metal cation(s) solution(s).In the second projection method, the association of several oxidizing metal cations to form a multilayer of different metals or alloys is such that the different metal cations are preferably projected naturally separately from the reducing agent but also separately from each other and successively.

[0112] According to a third spraying method, a metastable metallizing solution containing a mixture of at least one metal in the form of a metal cation ('oxidant(s)') and at least one reductant is sprayed as an aerosol. After spraying onto the substrate surface, the metallizing solution is activated to initiate the transformation of the metal cation(s) into metal, preferably by contact with an initiator, advantageously delivered via one or more aerosols, before, during, or after spraying the metallizing solution. The initiation or activation of the redox reaction may then be achieved by any suitable physical (temperature, UV, etc.) or chemical means.

[0113] Water appears to be the most suitable solvent, without excluding the possibility of using organic solvents, for the preparation of the metallization solution(s) to be projected in aerosol form(s).

[0114] The concentration(s) of metal salt(s) in the oxidizing solution(s) to be sprayed are preferably between 0.1 g / L and 100 g / L and preferably also between 1 g / L and 60 g / L. Where appropriate, the concentration(s) of metal salt(s) in the stock solution(s) are preferably between 0.5 g / L and 500 g / L, or the dilution factor of the stock solution(s) is preferably between 5 and 5,000. Advantageously, the metal salts are selected from silver nitrate, nickel sulfate, copper sulfate, tin chloride, aurochloric acid, iron chloride, cobalt chloride and mixtures thereof.

[0115] The selection of the reducing agent(s) is preferably made from among the compounds The following are suitable: borohydrides, dimethylaminoborane, hydrazine, sodium hypophosphite, formalin, lithium aluminohydride, reducing sugars such as glucose derivatives or sodium erythorbate, and mixtures thereof. Selecting the reducing agent requires consideration of the pH and the desired properties for the metal deposition. These routine adjustments are within the capabilities of a person skilled in the art. The concentration(s) of the metal salt(s) in the reducing solution(s) to be sprayed are preferably between 0.1 g / L and 100 g / L, and even more preferably between 1 g / L and 60 g / L. Where appropriate, the concentration(s) of the reductant(s) in the stock solution(s) are preferably between 0.5 g / 1 and 250 g / 1, or the dilution factor of the stock solution(s) is preferably between 5 and 2,500.

[0116] Optionally, additional particles, such as those envisaged above, may be incorporated into at least one of the metallization solutions to be sprayed onto the substrate during the metallization step D. The additional particles are thus advantageously trapped in the metallic deposit formed on the surface of the substrate.

[0117] As previously indicated, such a method of metallization by aerosol(s) projection is particularly interesting in that it allows in particular a simple and rapid metallization of substrates of all dimensions, and in particular of large substrates, and in that it is particularly well suited to the case where the metallization step D is carried out after the thermoforming step C (variant VI), and where the surface to be metallized is therefore not flat but on the contrary deformed.

[0118] Furthermore, such a metallization method by aerosol spraying makes it possible, in the context of the invention, to obtain a metallic deposit, possibly multilayered, with excellent properties, particularly in terms of adhesion to the substrate, thickness homogeneity, and surface finish (very low roughness). It is thus advantageously possible to obtain one or more metallic patterns exhibiting excellent electrical conductivity. Moreover, such a metallization method by aerosol spraying allows for particularly precise control of the thickness of the metallic deposit formed, which can therefore be transparent or opaque, depending on the intended applications.

[0119] — Non-electrolytic immersion deposition

[0120] In accordance with what has been described above, according to the embodiment in which the metallization of the substrate is carried out by autocatalytic (or "electroless") chemical deposition by immersion of the substrate in one (or more) metallization solution(s), the metallization step D may advantageously be preceded by a substrate activation step H, and possibly preceded, before said activation step H, of at least one of the following steps, preferably in the following order: - satin finishing step S, preferably implemented between step B of temporary masking coating formation and step H of activation; - step T of rinsing the surface of the substrate, in the event of implementation of such a step S of satin finishing.

[0121] Advantageously, the satinizing step S is a surface energy increase treatment step of the substrate as described previously with regard to non-electrolytic metallization by aerosol spraying (Step P). The same applies to the rinsing step T.

[0122] As previously introduced, the metallization step D, in this particular embodiment, is typically carried out by immersing the substrate in a bath (an "electroless" bath) of a metallization solution, optionally comprising, in addition to one or more metal cations and one or more reducing agents, one or more complexing agents, one or more stabilizing agents, and other possible additives (surfactants, etc.). Typically, during step D, the formation of the metal deposit occurs on all areas of the substrate on which a catalyst was previously deposited during the activation step H.

[0123] Insofar as the activation step H is preferentially carried out after the temporary masking coating formation step B and before the removal step E, the area(s) of the substrate covered by the temporary masking coating is (are) therefore not catalyzed, and therefore cannot be the site of the formation of a metallic deposit.

[0124] Preferably, the metallization step D is carried out here after the removal of the temporary masking coating step E. Indeed, if, on the contrary, the metallization step D were carried out before said step E, it would be advantageous to ensure that the temporary masking coating is designed so that the catalyst cannot be adsorbed onto its surface, and that said temporary masking coating is capable of withstanding the electroless bath, in order to limit the risk of contamination of said electroless bath.

[0125] —Electrolytic deposition

[0126] For more details on this metallization method which may be implemented in the metallization step D, reference may be made to the technical literature relating to this technology, and for example to treatises on electroplating.

[0127] - Step E of removal of the temporary masking coating -

[0128] In accordance with the above, step E can be carried out: - either (in its entirety) before the metallization step D, particularly in the case where the process includes a substrate surface activation step H prior to the metallization step D and where the temporary masking coating is intended to to allow selective activation of the substrate surface; - either (in full) after step D; - either, more preferably, (in whole) during step D, or partly during step D and partly after step D, or partly before step D, partly during step D and partly after step D.

[0129] As previously introduced, step E advantageously includes at least one dissolution operation, or even essentially consists of a dissolution, of the temporary masking coating by at least one solvent implemented in the process.

[0130] If the process includes a step I of rinsing the surface of the metallized substrate, step E of removing the temporary protection may optionally be carried out either during step I of rinsing, or partly during step D of metallization and at least partly during said step I of rinsing. If the process includes a step J of drying, step E of removing the temporary protection may optionally be carried out partly during step D of metallization and at least partly during said step J of drying.

[0131] The operation of dissolving the temporary masking coating can be carried out, for example, by spraying one (or more) aqueous solvent(s), by spraying one (or more) organic solvent(s), by spraying a mixture of aqueous and organic solvent(s), by immersion in a bath of aqueous solvent(s), by immersion in a bath of organic solvent(s), or by immersion in a bath of a mixture of aqueous and organic solvent(s). Optionally, said dissolution operation can be carried out with the application of heat, and thus be carried out at a temperature preferably between 30 °C and 90 °C, and more preferably between 50 °C and 80 °C. In practice, the timing of the execution of step E may depend in particular on the methods of execution of step D of metallization, and in particular on the metallization method(s) implemented during it.In particular, the removal of the temporary masking coating, at least partially, during metallization step D assumes that the methods used to carry out the latter allow it and that the residue produced by this removal is not such as to interfere with the proper progress of metallization step D.

[0132] — Non-electrolytic deposition by spraying in aerosol form(s)

[0133] In this embodiment, step E of removing the temporary masking coating can be carried out at least in part during step D, in the advantageous case mentioned above where a solvent suitable for dissolving the temporary masking coating is contained in the, or in at least one of the, metallizing solution(s) used during step D.

[0134] In practice, and even more preferably, the temporary masking coating is alkali-soluble (or at least alkali-sensitive), and the metallizing solution(s) has a strongly alkaline pH (typically above 9), so that the metallizing solution(s) can dissolve the temporary masking coating during step D. Typically, when the metallizing solution(s) is / are sprayed as an aerosol, the unmasked areas of the substrate are metallized, while the temporary masking coating is dissolved and flushed away in the effluent, thus revealing: - either the desired metallic pattern(s), in the case where step D is carried out after step C of thermoforming (variant VI); - either one (or more) corresponding "raw" metallic motif(s), as mentioned previously, in the case where step D is carried out before step C of thermoforming (Variant V2).

[0135] However, it is preferable that the metallization time, i.e. the time required to form the metallic deposit during step D, be limited, so as to prevent any risk of metallization of substrate areas that were initially covered by the temporary masking coating.

[0136] In this aerosol spray embodiment, it is possible, as a complement or alternative, particularly when the metallizing solution(s) used do not contain a solvent capable of dissolving the temporary masking coating, to rinse, for example by spraying, the masked and metallized surface of the substrate with one or more solvents capable of dissolving the temporary masking coating. The dissolution of the temporary masking coating is thus accompanied by the removal of any metallic deposit present on its surface.

[0137] —Non-electrolytic immersion deposition

[0138] In this alternative embodiment, which generally involves implementing an activation step H as described above, Step E can typically be carried out between Step H and the metallization step D by applying a solvent capable of dissolving the temporary masking coating to the surface of the masked substrate. Such an application can be carried out, for example, by immersing the masked substrate in said solvent or by spraying said solvent onto the surface of the masked substrate, followed by rinsing.

[0139] This dissolution reveals the activated area(s) of the substrate surface that can receive the metallic deposit intended to form the desired metallic pattern(s). The area(s) of the substrate surface that were previously covered by the temporary masking coating were not activated (catalyst adsorption) during step H, so that no metallic deposit was made there. will be formed for at least the time necessary for the formation of a metallic deposit on the activated area(s) of the substrate surface.

[0140] —Electrolytic deposition

[0141] In this embodiment, Step E, the removal of the temporary masking coating, may optionally be carried out, at least in part, during Step D, the metallization step, typically where the metallization solution used contains a solvent capable of dissolving the temporary masking coating and where the time required for the formation of the metal deposit by electrolytic deposition is advantageously less than or equal to the time required for the dissolution of the temporary masking coating by said solvent. Alternatively, or possibly in addition, Step E may be carried out after Step D, the metallization step, and for example during a Step I, the rinsing of the metallized substrate carried out using a rinsing liquid containing or forming a solvent capable of dissolving the temporary masking coating.

[0142] - Step I of rinsing the surface of the metallized substrate -

[0143] After the metallization step D, the process may include, as mentioned above, a rinsing step I of the surface of the metallized substrate. The rinsing step I, like the other rinsing steps (in particular steps P and R) that the process may include, may be carried out in any known and appropriate manner, for example by spraying / spraying one or more rinsing liquids using an HVLP spray gun or by soaking / immersing in one or more rinsing liquids. The latter is preferably water, and even more preferably demineralized water, except possibly in the case where the rinsing liquid contains or forms a solvent (other than water) for dissolving the temporary masking coating.

[0144] - Step J of drying the surface of the metallized substrate -

[0145] After step I, rinsing the surface of the metallized substrate, the process may include a step J, drying the surface of the metallized substrate. This drying step J, like any other drying steps that might occur after each rinsing step, consists of removing the rinsing liquid. Such drying can typically be carried out at ambient temperature by blowing a stream of compressed air, for example, at a pressure of 5 bar, or using an air blade system. Air drying or oven drying is also possible.

[0146] - Steps K, L, M of surface finishing treatment of the metallized substrate -

[0147] One (or more) additional "definition" step(s) may be added implemented after metallization step D, and preferably even after thermoforming step C if the latter is carried out after metallization step D, in order, for example, to protect the metallic pattern(s) formed from the deposit metallic with respect to external physical and / or chemical aggressions, and / or in order to modify or improve the properties of the metallic pattern(s), for example in terms of electrical conductivity and / or optical properties.

[0148] In this respect, the process may optionally include a supplementary metallization step K (or "thickening step") by forming at least one additional metal deposit on the surface of the (initial) metal deposit obtained at the end of the metallization step D. Such a supplementary metallization step K may advantageously be carried out by electrolytic deposition (for example, by electroplating) or by non-electrolytic ("electroless") deposition. This additional metal deposit may or may not have the same composition as the initial metal deposit. For example, the additional metal deposit may comprise, or be formed from, at least one metal selected from silver, nickel, copper, gold, iron, cobalt, tin, zinc, ruthenium, palladium, one or more oxides thereof, or one or more alloys thereof, or a combination thereof.Such a complementary metallization step K can be particularly useful when the initial metallization step D is carried out by non-electrolytic chemical deposition, as previously considered, and when one wishes to obtain one (or more) metallic pattern(s) with a total thickness greater than 5 pm.

[0149] Alternatively or complementarily, the process may optionally include a passivation step L of the metallic deposit(s) forming the metallic motif(s), in order to protect it / them against corrosion or oxidation. Typically, such a passivation step L can be carried out by spraying with, or by immersion in, at least one passivation solution adapted to the composition of the metallic deposit(s) forming the metallic motif(s), such as, for example, a solution of inorganic tin salt(s), an organic precious metal passivation solution such as is commonly available commercially, or an inorganic solution from the silane or silicon dioxide (SiOx) family.

[0150] Alternatively or complementarily, the process may optionally include – subsequent to said metallization step D and thermoforming step C, and preferably subsequent to step E of removal of the temporary masking coating – a step M of forming a topcoat covering the surface of the substrate (metallized thermoformed substrate) bearing the metallic pattern(s). Such a topcoat, organic or inorganic, may constitute a protective coating against mechanical friction, against oxidation, etc., and / or an electrical insulation coating, and / or a decorative coating. Step M of forming the topcoat may typically be carried out by deposition / application, using any known and suitable technique, at least one topcoat of a curable and / or crosslinkable liquid composition (e.g., by UV exposure or thermal curing) on ​​the surface of the substrate bearing the metallic pattern(s). The liquid composition may be a paint or varnish, advantageously selected, for example, from the following group: alkyds, polyurethanes, epoxies, vinyls, acrylics, and their mixtures. Preferably, the liquid composition is a varnish, possibly colored / pigmented, advantageously selected from the following compounds: epoxies, alkyds, and acrylics.

[0151] - Step N of overmolding -

[0152] Optionally, the process according to the invention may include, after thermoforming step C, an overmolding step N of the (thermoformed) substrate. Step N may be carried out after metallization step D if the latter is performed after thermoforming step C, or conversely, before metallization step D if the metal deposit / metal pattern(s) might be damaged during overmolding step N. Overmolding step N (or injection molding) advantageously consists of injecting a polymer material or a mixture of polymer materials, compatible with the nature of the thermoformed substrate material, into a mold in which the thermoformed (and preferably metallized) substrate has been previously positioned.Such an overmolding step can advantageously allow, for example, the formation of a protective and / or support piece for the thermoformed (and preferably metallized) substrate.

[0153] - Step O of assembling additional components -

[0154] For certain applications of the three-dimensional article, it may be desirable to assemble one or more electrical, electronic, and / or optoelectronic components (electrical connectors, electrical cables / wires, LEDs, electronic chips, etc.) to the thermoformed substrate provided with the metallic pattern(s), whether overmolded or not, either through-hole or surface-mounted. Advantageously, such an assembly step can be implemented using one or more robotic surface-mount component (SMD) placement systems, commonly known as "pick-and-place" or "P&P" machines, one or more robotic arms, or any other known and advantageously automated means of depositing liquids / components onto a 2.5D or 3D surface.Such an assembly step can advantageously be carried out by brazing and / or using an electro-conductive adhesive, isotropic or anisotropic, taking for example the form of a film or a paste, and of any suitable chemical nature (silicone, epoxy, acrylic, etc.). If necessary, a baking operation of the electro-conductive adhesive can be implemented.

[0155] In conclusion, the process according to the invention offers, in particular, the following advantages: - it makes possible the manufacture of three-dimensional articles, of all sizes and complex shapes, furnished with decorative and / or functional metal motifs, which can themselves be of large dimensions and / or complex shapes; - it allows the manufacture of three-dimensional articles with metallic patterns that can be particularly fine, precise and / or complex; - it allows the manufacture of three-dimensional articles with metallic patterns that are particularly resistant to external aggressions; - it allows the manufacture of three-dimensional articles with metallic patterns that are particularly homogeneous and regular, both in terms of thickness and in terms of surface appearance (very low roughness); - it allows the manufacture of three-dimensional articles with metallic patterns in a multitude of possible metals (pure metals, metallic alloys, metallic oxides, etc.); - it allows the manufacture of three-dimensional articles with metallic pattern(s) which can be used in a large number of technical applications, including among the most demanding and sensitive in terms of the properties of the metallic patterns (fineness, thickness, purity, electrical conductivity, roughness, etc.), the said metallic patterns being able to be decorative) and / or functional, and being able to advantageously form or contribute to form, for example and without limitation, one or more printed circuits, one or more integrated circuits on semiconductor substrate, one or more sensor / detector electrodes, one or more electrodes of an electrical heating / defrosting device, one or more radiating element(s) of radio frequency antenna (WiFi®, RFID, etc.), one or more coding pictograms capable of being read by electronic devices, one or more figurative and / or scriptural pieces of information identifying a product which incorporates or to which is associated said three-dimensional article, in particular a commercial product, such as a decorative visual or design on packaging, on an automotive product, etc.; . - it can be implemented in an industrial context for mass production; - it is particularly quick, simple and economical to implement.

[0156] Two examples of implementing a process according to the invention for manufacturing three-dimensional articles with metallic pattern(s) will now be described, in conjunction with the accompanying figures. Example 1 illustrates in particular the implementation of variant VI in which thermoforming step C is carried out before metallization step D, while Example 2 illustrates in particular the implementation of variant V2 in which step C of thermoforming is carried out after step D of metallization.

[0157] - Example 1 - Fabrication of a three-dimensional RFID antenna -

[0158] - Step A: a flat substrate is provided, consisting of a polycarbonate film of a 250 µm thick, and 330 mm long by 250 mm wide; - Step B: a temporary masking coating is formed by screen printing, from a thermodeformable and alkali-sensitive masking composition developed by JET METAL TECHNOLOGIES®, onto the polycarbonate film. The deposited masking composition layer is then dried by desolvation at 60° for 5 min. As illustrated in the example in [Fig. 1], the temporary masking coating thus formed delimits at least one unmasked area (in the center); - Step C: the selectively masked film is then heated homogeneously by infrared (IR) to 215 °C, and then placed on a counterform to thermoform it. [Fig.2] illustrates an example of a thermoformed masked film obtained after cooling and curing; - Step P / Step Q: the surface of the thermoformed masked film is subjected to a surface energy increase treatment by plasma treatment (so-called "air" plasma: 80% nitrogen / 20% oxygen at 0.5 mbar for 2 min), so that at the end of this treatment, the surface energy of the thermoformed masked film is greater than 50 dynes and said surface can be perfectly wetted by water spraying, the water then forming a continuous film on the surface of the thermoformed masked film; - Step H: a stannous chloride-based sensitization solution is projected onto the surface of the thermoformed masked film for 10 s using an HVLP gun; - Step R: the surface of the thermoformed masked film is rinsed to remove the sensitizing solution by spraying demineralized water for 10 s using an HVLP gun; - Step D / Step E: a metallic deposit is formed on the surface of the thermoformed masking film and sensitized by simultaneous projection of a first aqueous metallization solution (oxidizing solution) based on silver nitrate at a concentration of 2 g / l and having a pH > 9, and a second metallization solution (reducing solution) based on glucose, for 80 s using HVLP guns set at a spray pressure of less than 2.5 bar. Under the effect of the alkalinity of the first metallization solution, the temporary, alkali-sensitive masking coating is partially degraded and washed away from the surface of the substrate with the effluents, thus revealing the desired metallic pattern; - Step I: The surface of the metallized thermoformed film is rinsed with water using an HVLP spray gun. This rinsing removes any remaining coating residue. temporary masking. If necessary, additional rinsing is carried out by immersion in a bath or by spraying solutions containing an ethanol / isopropanol type solvent to guarantee a perfect absence of temporary masking coating residues and metallic deposits carried by them; - Step J: the surface of the metallized thermoformed film is dried at room temperature under an airflow of 5 bar. The result obtained is illustrated in [Fig.3], on which the thermoformed polycarbonate film and the solid elemental silver metallic pattern obtained on its surface form a three-dimensional RFID antenna; - Step O: an electronic RFID antenna chip is then assembled onto the metallized thermoformed film, either by soldering or using an electro-conductive adhesive; - Step M: the metallized surface of the three-dimensional article thus obtained is then coated with a protective varnish developed by the company JET METAL TECHNOLOGIES®.

[0159] - Example 2 - Manufacture of a three-dimensional article comprising patterns decorative silver lines

[0160] - Step A: a flat substrate is provided, consisting of a polycarbonate film of a 250 µm thick, and 380 mm long by 310 mm wide; - Step B: A temporary masking coating is formed by screen printing, using an alkali-sensitive masking composition developed by JET METAL TECHNOLOGIES®, onto the polycarbonate film. The deposited masking composition layer is then dried by desolvation at 80° for 5 minutes. As illustrated in the example in [Fig. 4], the temporary masking coating thus formed delimits a plurality of unmasked areas in the form of lines; - Step P / Step Q: the surface of the masked film is subjected to a surface energy increase treatment by direct corona ceramic treatment, at a speed of 3 m / min and in 3 passes, so that at the end of this treatment, the surface energy of the masked film is greater than 50 dynes and that said surface can be perfectly wetted by water spraying, the water then forming a continuous film on the surface of the masked film; - Step H: a stannous chloride-based sensitization solution is projected onto the surface of the masked film for 10 s using an HVLP gun; - Step R: the surface of the masked film is rinsed to remove the sensitizing solution by spraying demineralized water for 10 s using an HVLP gun; - Step D / Step E: a metallic deposit is formed on the surface of the masked and sensitized film by simultaneous projection of a first aqueous metallization solution (oxidizing solution) based on silver nitrate at a concentration of 2 g / L and having a pH > 9, and a second metallization solution (reducing solution) based on glucose, for 80 s using an HVLP gun. Under the effect of the alkalinity of the first metallization solution, the temporary, alkali-sensitive masking coating is partially degraded and removed from the surface of the substrate with the effluents; - Step I: the surface of the metallized film is then rinsed consecutively with water using an HVLP gun for 10 s, then with a rinsing liquid "SelectRinse" developed by the company JET METAL TECHNOLOGIES® for 15 s using an HVLP gun in order to remove any residues of the temporary masking coating, then again with water using an HVLP gun. - Step J: the surface of the metallized film is dried at room temperature under an airflow of 5 bar. [Fig. 5] illustrates the metallized film thus obtained as an example; - Step C: The selectively metallized film is then heated homogeneously by infrared (IR) to 215 °C, and then placed on a counterform to thermoform it. Figure 6 illustrates, as an example, the thermoformed masked film thus obtained after cooling and hardening, which can then form the three-dimensional article itself, or be subsequently used to form said three-dimensional article.

Claims

1.

2.

3.

4. Demands A method for manufacturing a three-dimensional article comprising at least one metallic motif, comprising at least: - a step A of supplying a flat substrate made of thermoformable material; - a step B of forming on a surface of the flat substrate a temporary masking coating which adheres to said surface, to obtain a masked substrate having at least one unmasked area; - a step C of thermoforming the flat substrate to give it a general three-dimensional shape; - a step D of metallization of the masked substrate to form a metallic deposit on the latter at least on said unmasked area; - and a step E of removing said temporary masking coating, thermoforming step C being carried out before metallization step D and before removal of said temporary masking coating step E, metallization step D being carried out by non-electrolytic deposition from one or more metallization solutions containing at least one metal in the form of a metallic cation and at least one reducer capable of transforming the metallic cation into metal, by spraying the metallization solution(s) in the form of one or more aerosols. A method according to the preceding claim, wherein the metallic deposit is made of solid metal. A process according to any one of the preceding claims, wherein the metal deposit has, at the end of the metallization step D, a thickness of between 10 nm and 5 pm, preferably between 10 nm and 1 pm, and preferably also between 10 nm and 500 nm. A method according to any one of the preceding claims, wherein step D is carried out such that the thickness of the metallic deposit is variable according to the extent of said metallic deposit, the metallic deposit having at least a first zone and a second zone, distinct, the thickness of the metallic deposit being increasing or decreasing from said first zone to said second zone.

5. A method according to any one of the preceding claims, wherein step E of removing the temporary masking coating is carried out during step D of metallization, or partly during step D of metallization and partly after step D of metallization, or partly before step D of metallization, partly during step D of metallization and partly after step D of metallization.

6. A process according to any one of the preceding claims, wherein step E of removing the temporary masking coating includes at least one operation of dissolving the temporary masking coating by at least one solvent used in the process, said temporary masking coating being preferably alkali-soluble so as to be able to be dissolved preferably by an alkaline solvent used in the process.

7. A method according to claims 5 and 6, wherein said solvent is contained in the or one of the metallizing solutions.

8. A method according to any one of the preceding claims, wherein step B of forming the temporary masking coating is carried out by selectively depositing a layer of a liquid or paste masking composition onto the surface of the flat substrate, for example by screen printing and / or direct printing, optionally followed by drying and / or curing the layer of masking composition.

9. A method according to any one of the preceding claims, wherein the temporary masking coating has, at the end of the step of forming the latter, a thickness of between 100 nm and 50 pm, preferably between 500 nm and 20 pm, and preferably still between 1 pm and 10 pm.

10. A method according to any one of the preceding claims, wherein the flat substrate is a film, sheet or plate of a thermoformable polymer material or of a thermoformable polymer matrix composite material, of a thickness preferably between 8 pm and 15 mm, and more preferably between 25 pm and 10 mm.

11. A method according to any one of the preceding claims, wherein it comprises a step G of defining a two-dimensional masking pattern, according to which the temporary masking coating is then formed on the surface of the flat substrate, from a model of a deformation of the flat substrate during step C of thermoforming and a representation of the metallic pattern to be obtained.

12. A method according to any one of the preceding claims, which comprises, subsequent to step C of thermoforming, a step N of overmolding the substrate.

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