Method for producing selectively metallised three-dimensional items with a masking coating composition

Abstract

The invention relates to a method for producing a selectively metallised three-dimensional item, the method comprising at least: - a step of depositing a composition in the liquid or paste state on a surface of a thermoformable substrate, the composition comprising at least one organic polymer matrix formed of one or more organic monomers and / or polymers, the composition comprising neither electrically conductive particles nor magnetic particles; - a step of curing the composition thus deposited on the substrate to form a film-forming masking coating that adheres to the latter, the masking coating having a thickness of between 0.1 pm and 30 pm; - a step of thermoforming the thus-coated substrate with the film-forming masking coating; - a step of metallising the substrate to form a metal deposit thereon; and - a step of removing the masking coating using an alkaline solution subsequent to or simultaneously with the step of metallising the substrate.

Description

[0001] PROCESS FOR MANUFACTURING SELECTIVELY METALLIZED THREE-DIMENSIONAL ARTICLES WITH A

[0002] MASKING COATING COMPOSITION

[0003] TECHNICAL FIELD

[0004] The present invention relates to the general technical field of techniques and means for the manufacture of three-dimensional articles with metallic pattern(s).

[0005] PRIOR TECHNIQUE

[0006] In the field of printed electronics, it is known to manufacture three-dimensional articles or objects locally covered by electrically conductive metallizations, in which conductive patterns are produced on a thermoplastic polymer substrate by direct printing (screen printing or inkjet) using an electrically conductive ink, such as in particular an ink loaded with silver particles. The substrate is then thermoformed to give it the desired three-dimensional appearance. In addition to 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 improvable, in particular in terms of the level and homogeneity of electrical conductivity, which can in certain cases prove problematic for the proper functioning of an electronic device integrating such a three-dimensional object.

[0007] STATEMENT OF THE INVENTION

[0008] The objects assigned to the invention therefore aim to provide a response to the aforementioned needs and problems, in order to manufacture in a simpler, more efficient and economical manner three-dimensional articles with decorative and / or functional metallic pattern(s), in a wide variety of shapes and geometries.

[0009] Another object of the invention is to enable the easy manufacture of three-dimensional articles with metallic pattern(s) of any size. Another object of the invention is to enable the rapid and relatively inexpensive manufacture of three-dimensional articles with metallic pattern(s).

[0010] Another object of the invention is to enable simple manufacture of three-dimensional articles with metallic pattern(s).

[0011] Another object of the invention aims to enable the manufacture of three-dimensional articles with metallic pattern(s) with controlled manufacturing costs.

[0012] Another object of the invention is to enable the manufacture of three-dimensional articles with metallic pattern(s) in a wide variety of dimensions and shapes.

[0013] Another object of the invention is to enable the manufacture of three-dimensional articles so that they have one or more fine, precise and / or complex metallic patterns.

[0014] Another object of the invention aims to enable the manufacture of three-dimensional articles whose metallic pattern(s) is (are) particularly resistant to external aggression.

[0015] Another object of the invention aims to enable the manufacture of three-dimensional articles whose metallic pattern(s) is (are) particularly homogeneous and regular, both in terms of thickness and in terms of surface appearance.

[0016] Another object of the invention aims to enable the manufacture of three-dimensional articles with metallic pattern(s) having excellent control of the shape of their metallic pattern(s).

[0017] The objects assigned to the invention are achieved using a method for manufacturing a selectively metallized three-dimensional article, comprising at least:

[0018] - a step of depositing a composition in the liquid or pasty state on a surface of a thermoformable substrate, said composition comprising at least one organic polymer matrix formed from one or more organic monomers and / or polymers, said composition comprising neither electrically conductive particles nor magnetic particles,

[0019] - a step of hardening said composition thus deposited on the substrate to form a film-forming masking coating adhering to the latter, said masking coating having a thickness of between 0.1 μm and 30 μm,

[0020] - a step of thermoforming the substrate thus coated with the film-forming masking coating,

[0021] - a step of metallization of the substrate to form a metallic deposit on the latter;

[0022] - and a step of removing the masking coating using an alkaline solution, after or concomitantly with the step of metallizing the substrate.

[0023] Also described below is a composition for producing a film-forming masking coating adhering to at least a portion of a surface of a substrate intended to be thermoformed for the manufacture of a selectively metallized three-dimensional article, said composition comprising at least one organic polymer matrix formed from one or more organic monomers and / or polymers, said polymer matrix being curable to form said masking coating which, after curing, for a thickness of between 0.1 μm and 50 μm, has a deformation rate before rupture of greater than 30%, at a temperature of between 20°C and 270°C.

[0024] Also described below is a film-forming masking coating, produced from the deposition, on a surface of a substrate intended to be thermoformed for the manufacture of a selectively metallized three-dimensional article, of at least one layer of the composition according to the above, for example by screen printing and / or by direct printing followed by curing of said composition. Also described below is the use of a composition as mentioned above for producing a film-forming masking coating on the surface of a thermoformable flat substrate.

[0025] Other features and advantages of the invention will appear and emerge in more detail upon reading the description given below.

[0026] BEST WAY TO CARRY OUT THE INVENTION

[0027] The invention relates, according to a first aspect, to a composition for producing a film-forming masking coating adhering to at least a portion of the surface of a substrate. Said substrate is intended to be thermoformed for the manufacture of a selectively metallized three-dimensional article. The composition of the invention is therefore advantageously designed to be implemented in the manufacture of a three-dimensional article comprising at least one metallic pattern (or "metallized pattern").

[0028] For the purposes of the invention, the term “three-dimensional” means a physical object that develops substantially in the three dimensions of space, at non-negligible distances from each other. The shape and dimensions of the metal pattern(s) are not particularly limited, and may in particular depend on the intended application of the three-dimensional article and the metal pattern(s) carried by the latter. Advantageously, the metal pattern(s) concerned is / are decorative and / or functional, and thus forms or contributes to forming, for example and in a non-limiting manner, one or more printed circuits, 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 radiofrequency antennas (WiFi®, RFID, etc.).), one or more coding pictograms capable of being read by electronic devices, one or more figurative and / or scriptural information identifying a product which incorporates or with which said three-dimensional article is associated, in particular a commercial product, such as a decorative visual or design on packaging, on an automotive product, etc. The substrate is advantageously flat and thermoformable, in particular it is formed from one or more thermoplastic materials. Furthermore, the masking coating is film-forming, that is to say it is advantageously capable of producing a coherent and / or continuous layer of material on a surface, and in particular on at least part of the surface of the substrate.

[0029] According to the invention, said composition comprises at least one organic polymer matrix formed from one or more organic monomers and / or polymers, said polymer matrix being curable to form said masking coating which, after curing, for a thickness of between 0.1 μm and 50 μm, has an elongation rate before breaking greater than 30%, at a temperature of between 20°C and 270°C.

[0030] The composition in accordance with the invention can advantageously be implemented in the following manner for the production of a selectively metallized three-dimensional article:

[0031] - application of the composition to the surface of the substrate, which is therefore advantageously flat and made of thermoformable material (for example a thermoplastic polymer), for example by screen printing or direct printing;

[0032] - curing of the polymer matrix, thus forming the masking coating, which then constitutes a film adhering to the surface of the substrate. The substrate then has a masked area, i.e. an area covered by the masking coating, as well as an unmasked area, i.e. an area not covered by the masking coating;

[0033] - thermoforming of the substrate to give it a general three-dimensional shape;

[0034] - metallization of the substrate to form a metallic deposit on the latter, in particular in the unmasked area;

[0035] - possibly, removal of said masking coating, which is therefore preferably temporary, for example using an alkaline solution. The removal of the masking coating may be subsequent to or concomitant with the metallization of the substrate.

[0036] Thus, the invention further relates, according to a second aspect, to a method for manufacturing a selectively metallized three-dimensional article. Of course, the elements described for the composition described here are advantageously also valid for the manufacturing method of the invention, and vice versa. The manufacturing method thus comprises at least one step of depositing a composition in the liquid or pasty state on a surface of a thermoformable substrate, said composition comprising at least one organic polymer matrix formed from one or more organic monomers and / or polymers. According to the second aspect of the invention, said composition does not comprise electrically conductive particles or magnetic particles. The manufacturing method further comprises at least one step of curing said composition thus deposited on the substrate to form a film-forming masking coating adhering to the latter.In other words, at the end of the curing step, the masking coating advantageously adheres by bonding to at least part of the surface of the substrate, for example in the manner of a mask. Such bonding can be carried out without adding adhesive material separate from the composition, the hardening of the latter on the substrate during the curing step advantageously making it possible to bond the masking coating thus formed to the substrate. The masking coating then preferably constitutes a layer of material covering (in part) said substrate and bonded to the latter, which will in particular prevent the metallization of the surface of the substrate covered by the masking coating during the metallization step as will be seen later.

[0037] According to the second aspect of the invention, said masking coating has a thickness of between 0.1 μm and 30 μm. The manufacturing method also comprises a step of thermoforming the substrate thus coated with the film-forming masking coating.

[0038] Preferably, during the thermoforming step, the substrate is brought to a thermoforming temperature of between 20°C and 270°C, preferably between 50°C and 250°C, more preferably between 70°C and 230°C.

[0039] The unmasked area may for example be produced by selective application of the composition to only part of the surface of the substrate which then constitutes the masked area, the other part therefore constitutes the unmasked area. Alternatively, the unmasked area is produced for example by mechanical removal of a portion of the coating (for example by cutting, scraping, etc.). During thermoforming of the substrate, preferably "hot" (temperature between 50°C and 250°C for example), that is to say during said thermoforming step, the masking coating, which therefore covers part of the substrate, undergoes deformation like the latter.Thanks to its elongation capabilities, the masking coating adhering to the substrate maintains high cohesion (without significant "fracture" of the coating), and above all does not "bleed" onto the unmasked area of ​​the substrate, which is then selectively covered by a layer of metal, for example using a spray, i.e. by spraying a metallization solution in the form of one or more aerosols onto the surface of the substrate. The masked area of ​​the substrate, being covered by the masking coating formed from said composition, is not covered by the metallization solution. In particular, the presence and possibly the removal of said masking coating make it possible to obtain a particularly precise, defect-free metallized area (in essence, the area not previously masked by the masking coating), quickly and economically.The composition of the invention cleverly makes it possible to form a (selective) masking coating, preferably temporary, adhering to the surface of the substrate, prior to thermoforming this substrate. For the selective metallization of the substrate, it thus advantageously becomes 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, it proves in practice much easier to carry out masking (preferably temporary) on a substrate (preferably flat) than on a three-dimensional substrate, which is also of complex shape / geometry, and the use of such a masking coating (preferably temporary) then makes it possible to easily and precisely metallize a wide variety of substrates made of thermoformable material, according to a plurality of conceivable metallization techniques.

[0040] Thus, according to the second aspect of the invention, the manufacturing method comprises at least:

[0041] - a step of metallization of the substrate to form a metallic deposit on the latter;

[0042] - and a step of removing the masking coating using an alkaline solution, after or concomitantly with the step of metallizing the substrate. Said alkaline (or basic) solution has a pH which is advantageously strictly greater than 7, more advantageously equal to or greater than 9.

[0043] Thus, the masking coating is advantageously temporary, and intended to be removed before and / or during the selective metallization of the three-dimensional substrate, during said removal step.

[0044] During said metallization step, the metal deposition is therefore advantageously carried out only on a portion of the surface of the substrate not covered by the masking coating. The metal deposit adheres to the substrate. When the masking coating is removed from the substrate during said removal step, the surface of the substrate which was covered by the masking coating is therefore preferably free, i.e. not covered, or at least covered neither by the masking coating nor by the metal deposit.

[0045] The metal deposit is preferably made of solid metal. The term "solid metal metal deposit" therefore advantageously means in particular that the metal deposit is advantageously free of polymer matrix. This makes it possible in particular to obtain a metal pattern whose properties remain particularly stable over time, unlike a pattern which would comprise a polymer matrix in which metal particles would be dispersed, which polymer matrix would then be liable to gradually degrade under the effect, for example, of light, heat, etc., thus leading to a drift over time of the properties of the metal pattern. Advantageously, the solid metal may consist of a single pure elemental metal (typically more than 90%, preferably more than 95%, and more preferably more than 98%).For example, the metal deposit may thus be formed from a pure elemental metal, for example pure silver Ag (preferably more than 95%, and more preferably more than 98%), and possibly additional particles (for example diamond carbon particles, silicon carbide SiC particles, molybdenum disulfide M0S2 particles, particles of one or more rare earths or rare earth oxide(s), graphene particles, particles of a fluoropolymer such as polytetrafluoroethylene PTFE, particles of elemental metal or metal oxide(s), etc.).

[0046] Advantageously, the metal deposit has, at the end of the metallization step, a thickness of between 10 nm and 5 μm, preferably between 10 nm and 1 μm, and more preferably between 10 nm and 500 nm. According to a variant, the metallization step is carried out in such a way that the thickness of the metal deposit obtained at the end of the metallization step is substantially constant over the entire extent of said metal deposit, i.e. the thickness is substantially identical at every point of the metal deposit. It is thus possible to obtain one or more metal patterns which have a thickness which is substantially constant over the entire extent of the metal pattern(s).According to another variant, the metallization step is carried out in such a way that the thickness of the metal deposit obtained at the end of the metallization step is variable according to the extent of said metal deposit (while preferably remaining within the aforementioned ranges of values), that is to say that the metal deposit has at least a first zone and a second zone, distinct, the thickness of the metal deposit being increasing or on the contrary decreasing (thickness gradient) from said first zone towards said second zone. Such a variation in the thickness of the metal deposit thus advantageously makes it possible to obtain one or more metal pattern(s) which 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 radiofrequency waves, etc.), which may be of particular interest depending on the functional and / or decorative applications targeted.

[0047] Preferably, said composition is designed to be liquid or pasty at the temperature at which it is applied to the substrate, during said deposition step, and in particular is advantageously liquid or pasty at a temperature between 20°C and 50°C.

[0048] Advantageously, the organic polymer matrix and / or the masking coating is alkali-sensitive, and / or alkali-soluble, so as to be able to be preferentially dissolved by an alkaline solvent (i.e. with a pH strictly greater than 7). According to a particular embodiment, compatible with the above, the organic polymer matrix and / or the coating is soluble and / or dispersible in a liquid, for example an aqueous solution, having a pH equal to or greater than 9.

[0049] The metallizing solution may possibly dissolve the temporary masking coating during the metallization of the substrate. The metallization and removal steps are then at least partly concomitant. For example, when the metallizing solution is sprayed in the form of aerosol(s), the unmasked area of ​​the substrate is metallized, while the temporary masking coating is dissolved and discharged in the effluent, thus revealing the area previously masked by the masking coating.

[0050] In some cases, the masking coating may be intended to allow selective activation of the substrate surface, such that, at the end of the removal step, only at least one area of ​​the substrate surface not masked by the masking coating will be activated and will be able, during metallization, to receive a metal deposit to form one or more metal patterns.

[0051] According to one variant of the invention, the thermoforming step is carried out before the metallization step. According to another variant of the invention, the thermoforming step is carried out after the metallization step.

[0052] The thermoforming step is preferably carried out before the removal step. This obviously makes it possible to take advantage of the masking characteristics (non-metallization of the areas of the substrate masked by the coating) and elongation (during thermoforming of the substrate) of the masking coating adhering to the substrate. Advantageously, during said thermoforming step, the surface of the substrate thus covered by the masking coating is deformed.

[0053] Advantageously, the organic matrix comprises at least one monomer and / or one polymer chosen from: acrylic compounds, polyesters, vinyl compounds, styrenic compounds, polyamides, acrylate compounds, and / or cationic or anionic polymers.More specifically, said organic matrix preferably comprises at least one or more of the following compounds: PETIA (pentaerythritol triacrylate), HDDA (hexanediol diacrylate), IBOA (isobornyl acrylate), TMPTA (trimethylolpropane triacrylate), TPGDA (tripropylene glycol diacrylate), HEMA (hydroxyethyl methacrylate), vinyl chloride and acetate copolymer, acrylic resin, polyvinyl alcohol, polyvinylpyrrolidone, polyurethane, styrene acrylic copolymer, aliphatic urethane acrylate, polyester acrylate, polyester, methyl methacrylate and ethyl acrylate copolymer, methyl methacrylate and butyl methacrylate copolymer, monofunctional acrylate monomer, and / or trifunctional acrylate monomer.

[0054] The exact nature of the organic matrix is ​​preferably at least partly dependent on the nature of the substrate, as well as the thermoforming temperature of the latter, and is therefore preferably determined from the various characteristics of the coating and / or the composition set out here. The organic matrix provides the composition with important properties such as its adhesion to the substrate, its resistance to friction, its ability to wet one or more possible solids of the composition, and more particularly its elongation capacity (or deformation rate), its ability to flow under the effect of heat and its sensitivity to alkaline products (advantageous when it is necessary to remove the coating after and / or during the metallization of the substrate).

[0055] The substrate is preferably made of thermoformable polymer material (thermoplastic material), filled or not, or of a composite thermoformable material with a polymer matrix. Indeed, thermoformable polymer or polymer matrix materials are in particular generally easier to process, due to a softening temperature much lower than that of glass or most metals. Among the thermoformable polymer materials that can be considered forming the substrate, 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), or thermoplastic polyesters, such as, for example, polylactic acid (PLA), polyethylene terephthalate (PET) and glycolized polyethylene terephthalate (PETG).In the case where the flat substrate is a composite thermoformable material with a polymer matrix, the polymer(s) of the polymer matrix may be chosen, for example, from the thermoformable polymer materials listed above. More generally, the thermoformable material of the substrate may be a single material or, on the contrary, a composite material.

[0056] According to an advantageous variant of the second aspect of the invention, at the end of the deposition step and the curing step, the masking coating adheres to at least a first zone of the substrate, while at the end of the metallization step and the removal step, the metal deposit adheres to at least a second zone and a third zone of the substrate separated from each other by said first zone, no short circuit or metal bridge connecting said second and third zones via said first zone. Obviously, said first, second and third zones are preferably distinct. Said second and third zones are preferably non-adjacent, since they are separated from each other by said third zone.One of the advantages of the invention, and more particularly of the manufacturing method, is to obtain a precisely metallized three-dimensional substrate, that is to say that the substrate has a metallic pattern without short circuit, or metallic bridge, connecting parts of the metallic pattern in an undesirable manner, thus at the risk of short circuiting it.

[0057] Advantageously, the composition is designed so that the coating has, for a thickness of between 0.1 μm and 30 μm, for example (approximately) equal to 5 μm (+ / - 1 μm), a deformation rate before rupture greater than 100%, preferably greater than 300%, more preferably greater than 600%, even more preferably greater than 1000%, at a temperature of between 20°C and 270°C, preferably between 50°C and 250°C, more preferably between 70°C and 230°C.

[0058] In other words, advantageously, at the thermoforming temperature (and for a thickness between 0.1 μm and 30 μm thick), the masking coating has a deformation rate before rupture which is (at least) greater than 30%. Advantageously, the deformation rate before rupture is greater than 100%, preferably greater than 300%, more preferably greater than 600%, more preferably still greater than 1000%. The measurement of the deformation rate is advantageously carried out from the thermoforming of a grid pattern. According to a particular embodiment, a pattern of squares formed by said composition of 5 mm spaced 300 μm apart is printed by screen printing on an A4 format of thermoformable substrate. The pattern appearing after curing and metallization is a grid of lines 300 μm wide. The substrate is thermoformed into various shapes of different heights. The sample is metallized and the coating is removed.The metallized grid allows us to qualify the deformation rate that the masking coating can withstand. Thus, the measurement of the deformed square allows us to obtain the elongation that the coating can withstand without altering its ability to be removed in an alkaline environment. The measurement stops from the square where there is a short circuit between the parallel lines of the square.

[0059] The strain rate before failure is calculated as follows: 100 = strain rate

[0060] The distance is measured using a caliper.

[0061] In more detail, the rate of deformation before failure is preferably measured with a thermoforming test of a substrate coated with a grid pattern in masking coating, where the steps of the manufacturing process are reproduced so that:

[0062] - the deposition step and the curing step make it possible to obtain a substrate coated with the masking coating according to a pattern having squares in masking coating, said squares being of the same size and spaced from each other regularly by grid lines not covered by the masking coating, said squares being for example 5 mm on each side and said grid lines being for example 300 μm wide,

[0063] - during the step of thermoforming the substrate thus coated with the square pattern in masking coating, the substrate is deformed into shapes of different heights, so as to obtain a pattern of deformed squares in masking coating, - during the step of metallizing the substrate, the metal deposition is carried out on the substrate at the level of said grid lines, to form metallized grid lines,

[0064] - during the step of removing the masking coating, the pattern of deformed squares in masking coating is removed from the substrate, to form a pattern of deformed squares of the substrate free of masking coating, said free deformed squares being separated from each other by the metallized grid lines;

[0065] - the measurement of the deformation rate before rupture is carried out from the free deformed square of smallest width in which there is a short circuit or metallic bridge between two opposite, non-intersecting metallized grid lines of said square, the deformation rate before rupture being calculated as follows: „ „ „ , , , r 100 = deformation rate.

[0066] Expressed another way, to evaluate the deformation rate before rupture, squares of masking coating are produced, distributed regularly on and bonded to the substrate during the deposition and curing steps. The areas of the substrate that are not covered by the coating then form a grid comprising free grid lines, each square of masking coating on the substrate being surrounded by four grid lines, the opposite ones of which are parallel in pairs, and the intersecting ones are perpendicular in pairs. Said substrate is then hot deformed during the thermoforming step, thus deforming the squares to obtain deformed squares of masking coating.The deformed squares in masking coating are then removed from the substrate during the removal step and the substrate is metallized during the metallization step, so that a metal deposit is formed on and adheres to the surface of the substrate only in the areas of the latter which have not been covered by the masking coating. The metal deposit then forms a metal grid adhering to the substrate, said metal grid comprising metallized grid lines. These metallized grid lines define a pattern of deformed squares of the substrate, said squares being free of masking coating at the end of the removal step. For each free deformed square, it is necessary to avoid a short circuit (also called a metal bridge) between two opposite, non-intersecting metallized grid lines on the surface of said square.Indeed, the presence of such a short circuit or metal bridge means that during the thermoforming step, the masking coating, being stretched and deformed, has undergone a crack large enough to allow the metallization of the substrate at the level of said crack (and therefore at the level of the free deformed square), thus connecting two opposite metallized grid lines by short-circuiting them in an undesired manner. It is therefore necessary to select the free deformed square of smallest width having such a short circuit or metal bridge as the limit of the measurement, and to measure its width to report it in the formula mentioned above. The metallization and elimination steps can be at least partly concomitant, or the metallization step can take place before the elimination step.

[0067] The masking coating is advantageously thermoformable, that is to say it preferentially has thermoplastic properties. Its thermoformable nature explains or contributes to explaining its excellent elongation capacities, that is to say in essence its high deformation rate before rupture.

[0068] Advantageously, the organic polymer matrix forms between 20 and 80% of the total weight of the composition, although it may, in a particular alternative, form all or almost all of the total weight of the composition.

[0069] Preferably, the composition further comprises one or more solvents, said solvent(s) forming between 15 and 80% of the total weight of the composition, preferably between 20 and 75% of the total weight of the composition, for example between 30 and 60% of the total weight of the composition. The solvent may advantageously, in the case of curing by thermal drying, be intended to evaporate during the curing of the composition. The solvent advantageously allows the composition to have a liquid or pasty state.

[0070] Said solvent(s) advantageously comprise at least one or more of the following compounds: isopropanol, butanol, methoxypropanol, ethyl acetate, butyl acetate, cyclohexane, 2-butoxyethanol acetate, 2-methoxy-1-methylethyl acetate, propylene carbonate, isopropyl myristate, diethylene glycol monoethyl ether acetate, glycerol, heavy naphtha, hexane, and / or methylcyclohexane. According to a particular variant of the invention, said solvent(s) comprise at least water. When the composition comprises water, this optionally makes it possible to dissolve a monomer or a polymer of the organic matrix, an additive or another solvent, or to constitute a dispersion medium.

[0071] Advantageously, the composition is free of metallic and / or electrically conductive particles. In other words, the composition is designed so that the masking coating does not comprise metallic particles and / or electrically conductive particles. More specifically, neither the composition nor the coating contains electrically conductive solid metallic particles, or only in proportions that are sufficiently low so that the conductivity of the composition and / or the coating is very low, for example substantially of the same order of magnitude as that of an insulating material (polyethylene for example). In other words, the composition is preferably designed so that the coating is electrically insulating and / or dielectric.The advantage of such a configuration is that the composition has a relatively low manufacturing cost, and that in the case where it is not removed or not completely removed from the substrate after and / or during metallization, the non-conductive coating does not "interfere" with the metallized surface part of the three-dimensional thermoformed substrate.

[0072] Advantageously, the composition further comprises at least one dispersed organic or inorganic solid, said solid preferably being formed by powdery particles dispersed within the other constituents of said composition. This solid can give the composition its color, part of its rheological properties and part of its resistance to friction. Advantageously, said solid comprises a mineral filler, an organic filler, and / or a fibrous filler. Said mineral, organic and / or fibrous filler is preferably in the form of a multitude of small solid particles, advantageously in powder form. Said solid preferably comprises at least one or more of the following compounds: silica, calcium carbonate, barium sulfate, aluminum hydroxide, and / or a wax.Said solid advantageously forms between 0.5 and 50%, preferably between 1 and 40%, more preferably between 1.5 and 30%, more preferably still between 2 and 20%, of the total weight of the composition. The composition is advantageously designed so that the hardening of the polymer matrix is ​​carried out by (thermal) drying and / or application of ultraviolet rays.

[0073] The hardening of the polymer matrix advantageously corresponds to the polymerization and / or crosslinking of the latter.

[0074] Thus, said composition comprises, according to a particular embodiment, at least one radical, cationic or anionic photoinitiator agent, advantageously capable of crosslinking at least part of the polymer matrix when the composition is subjected to ultraviolet rays. This is particularly advantageous when the curing of the composition is carried out by means of ultraviolet rays.

[0075] Advantageously, the photoinitiating agent forms between 0.5 and 15%, preferably between 1 and 10%, more preferably between 1% and 7%, of the total weight of the composition. The photoinitiating agent advantageously comprises at least one of the following compounds: benzophenone, 1-hydroxy-cyclohexyl-phenyl-ketone, dimethylhydroxyacetophenone, diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide, 1-chloro-4-propoxythioxanthone, 2,2-dimethoxy-1,2-phenylacetophenone

[0076] The composition optionally comprises at least one or more of the following additional compounds: rheology agent, wetting agent, antifoam, dispersant, surfactant, stabilizer, colorant, synergist amine. The additional compound(s) preferably form between 0.01 and 10% of the total weight of the composition.

[0077] Preferably, the composition is designed so that the coating has a glass transition temperature and / or a melting temperature lower than the glass transition temperature of the substrate.

[0078] The different components of the composition allow it to be given suitable characteristics for different means of application on different substrates. An example of some characteristics is illustrated in Table 1. Table 1

[0079] For example, for an inkjet composition (i.e. "ink jet", which is a type of direct printing), the desired dynamic viscosity at 25°C is between 1 mPa.s and 1000 mPa.s at 25°C, preferably between 1 mPa.s and 30 mPa.s with temperature rise (in use), with a surface tension between 10 mN / m and 72 mN / m, and a particle size of the particles or aggregates (i.e. in particular the solid(s)) between 50 nm and 20 pm, preferably between 70 nm and 5 pm, more preferably between 100 nm and 500 nm.

[0080] The composition is preferably capable of being applied to the substrate in any suitable manner (depending on the substrate and the desired result), for example by screen printing, pad printing, flexography, gravure printing and / or direct printing (for example, drop-by-drop or "inkjet"). Thus, said deposition step is, according to an advantageous embodiment, carried out at least in part by screen printing and / or direct printing.

[0081] According to a first example in accordance with the invention, given for illustrative and non-limiting purposes, the composition comprises:

[0082] - a polymer matrix formed i) from methyl methacrylate and ethyl acrylate copolymer, which copolymer represents between 10% and 20% of the total weight of the composition, ii) from methyl methacrylate and butyl methacrylate copolymer, which copolymer represents between 10% and 20% of the total weight of the composition, ill) from a polyamide representing between 5% and 25% of the total weight of the composition, the polymer matrix therefore representing between 25% and 65% of the total weight of the composition;

[0083] - a solvent formed from a mixture of methoxypropanol and 2-butoxyethanol, which solvent represents between 30% and 75% of the total weight of the composition;

[0084] - a solid in the form of an organic spherical filler (for example a powder), which solid represents between 2% and 10% of the total weight of the composition, and has a melting temperature of less than 110°C;

[0085] - an antifoam and spreading additive, representing between 1% and 5% of the total weight of the composition.

[0086] The composition of this first example is capable of undergoing curing by drying (thermal) and can be applied to the substrate with a screen printing mask.

[0087] According to a second example in accordance with the invention, given by way of illustration and without limitation, the composition comprises: - a polymer matrix formed i) from an aqueous dispersion of polyurethane with 35% dry extract, the polyurethane (dry extract) representing between 10% and 25% of the total weight of the composition, ii) methyl methacrylate and ethyl acrylate copolymer, which copolymer represents between 10% and 20% of the total weight of the composition, ii) a trifunctional acrylate monomer representing 5% to 20% of the total weight of the composition, ll) a monofunctional acrylate monomer representing 5% to 15% of the total weight of the formulation, the polymer matrix therefore representing between 20% and 60% of the total weight of the composition;

[0088] - a solvent formed from a mixture of i) the aqueous phase in which polyurethane is dispersed, and ii) 2-butoxyethanol, which solvent represents between 20% and 60% of the total weight of the formula;

[0089] - an antifoam and spreading additive, representing between 1% and 5% of the total weight of the composition;

[0090] - a radical photoinitiator representing between 1% and 7% of the total weight of the formulation.

[0091] The composition of this first example is capable of undergoing curing by application of ultraviolet (UV) light and can be applied to the substrate in different ways (screen printing, direct printing, etc.).

[0092] According to a particular embodiment, the thickness of the masking coating has at least a first portion and a second portion, distinct from each other, the thickness of the first portion being different from the thickness of the second portion. In other words, the thickness of the masking coating can be variable depending on the extent of the latter (while preferably remaining within the aforementioned ranges of values). Such a difference in thickness of the masking coating, preferably within the ranges of values ​​indicated previously, may prove to be of interest according to certain embodiments, for example to locally adapt the thickness of the masking coating to the deformation rate to which a given area of ​​the substrate is to be subjected during the thermoforming of the latter.

[0093] According to a third aspect, the invention relates to a film-forming masking coating.

[0094] This coating is produced from the deposition, on a surface of a substrate intended to be thermoformed for the manufacture of a selectively metallized three-dimensional article, of at least one layer of the composition as mentioned above, for example by screen printing and / or by direct printing followed by curing of said composition. Said curing can advantageously be carried out by application of ultraviolet rays or drying. The masking coating is preferably, as indicated above, alkali-sensitive and / or alkali-soluble, and dissolves and / or disperses advantageously in a solution with a pH greater than or equal to 9. Of course, the elements described for the composition and the process described above are also advantageously valid for the masking coating, and vice versa.

[0095] Preferably, the masking coating has a thickness of between 0.1 μm and 30 μm, preferably between 1 μm and 20 μm, more preferably between 3 μm and 10 μm. Such a thickness makes it possible to obtain a sufficient barrier effect on the surface of the areas of the substrate which are not intended to subsequently carry the metal pattern(s). Furthermore, such a thickness advantageously contributes to the ability of the masking coating to undergo thermoforming without significant damage, if necessary.

[0096] According to a fourth aspect, the invention relates to the use of a composition as mentioned above for producing a film-forming masking coating (preferably thermoformable) on the surface of a substrate intended to be thermoformed for the manufacture of a selectively metallized three-dimensional article. Of course, the elements described for the composition, the method and the masking coating described above are advantageously also valid for the aforementioned use, and vice versa.

[0097] POSSIBILITY OF INDUSTRIAL APPLICATION

[0098] The invention finds application in the general technical field of the manufacture of three-dimensional articles provided with metallic, decorative and / or functional pattern(s).

Claims

DEMANDS 1. A method for manufacturing a selectively metallized three-dimensional article, comprising at least: - a step of depositing a composition in liquid or paste state onto a surface of a thermoformable substrate, said composition comprising at least one organic polymer matrix formed of one or more monomers and / or organic polymers, said composition not comprising electrically conductive particles or magnetic particles, - a hardening step of said composition thus deposited on the substrate to form a film-forming masking coating adhering to the latter, said masking coating having a thickness between 0.1 pm and 30 pm, - a thermoforming step of the substrate thus coated with the film-forming masking coating, - a metallization step of the substrate to form a metallic deposit on it; - and a step of removing the masking coating using an alkaline solution, either after or concurrently with the substrate metallization step.

2. Manufacturing process according to the preceding claim, characterized in that during the thermoforming step, the substrate is brought to a thermoforming temperature of between 20 °C and 270 °C, preferably between 50 °C and 250 °C, more preferably between 70 °C and 230 °C.

3. A manufacturing process according to the preceding claim, characterized in that, at the thermoforming temperature, the masking coating exhibits a deformation rate before breakage that is greater than 30%, the deformation rate before breakage being measured by a thermoforming test of a substrate coated with a grid pattern in masking coating, wherein the steps of the manufacturing process are reproduced so that: - the deposition and hardening stages allow a substrate coated with the masking coating to be obtained according to a pattern having squares in masking coating, said squares being of the same dimension and spaced from each other regularly by grid lines not covered by the masking coating, said squares being for example 5 mm on each side and said grid lines being for example 300 pm wide, - during the thermoforming stage of the substrate thus coated with the square pattern in masking coating, the substrate is deformed into shapes of different heights, so as to obtain a pattern of deformed squares in masking coating, - During the substrate metallization stage, the metallic deposit is made on the substrate at the level of the aforementioned grid lines, to form metallized grid lines, - during the masking coating removal step, the pattern of distorted squares in the masking coating is removed from the substrate, to form a pattern of distorted squares of the substrate free of masking coating, said free distorted squares being separated from each other by the metallized grid lines; - The measurement of the strain rate before failure is carried out using the smallest freely deformed square in which there is a short circuit or metallic bridge between two opposing, non-intersecting metallic grid lines of said square, the strain rate before failure being calculated as follows: " " " , , , r 100 = deformation rate. Manufacturing process according to the preceding claim, characterized in that the deformation rate before breakage is greater than 100%, preferably greater than 300%, more preferably greater than 600%, more preferably still greater than 1000%. A manufacturing process according to any one of the preceding claims, characterized in that, after the deposition and curing steps, the masking coating adheres to at least a first zone of the substrate, while after the metallization and removal steps, the metallic deposit adheres to at least a second and a third zone of the substrate separated from each other by said first zone, with no short circuits or metallic bridges connecting said second and third zones via said first zone. A manufacturing process according to any one of the preceding claims, characterized in that said organic matrix comprises at least one monomer and / or polymer selected from: acrylic compounds, polyesters, vinyl compounds, styrenic compounds, polyamides, acrylate compounds, and / or cationic or anionic polymers.A manufacturing process according to any one of the preceding claims, characterized in that said organic matrix comprises at least one or more of the following compounds: PETIA (pentaerythritol triacrylate), HDDA (hexanediol diacrylate), IBOA (isobornyl acrylate), TMPTA (trimethylolpropane triacrylate), TPGDA (tripropylene glycol diacrylate), HEMA (hydroxyethyl methacrylate), vinyl chloride and acetate copolymer, acrylic resin, polyvinyl alcohol, polyvinylpyrrolidone, polyurethane, styrene acrylic copolymer, aliphatic urethane acrylate, polyester acrylate, polyester, methyl methacrylate and ethyl acrylate copolymer, methyl methacrylate and butyl methacrylate copolymer, monofunctional acrylate monomer, and / or trifunctional acrylate monomer.A manufacturing process according to any one of the preceding claims, characterized in that said organic matrix comprises at least a methyl methacrylate and ethyl acrylate copolymer preferably forming between 10 and 20% of the total weight of the composition, a methyl methacrylate and butyl methacrylate copolymer preferably forming between 10 and 20% of the total weight of the composition, and a polyamide preferably forming between 5 and 25% of the total weight of the composition.

9. A manufacturing process according to any one of the preceding claims, characterized in that said organic matrix comprises at least polyurethane preferably forming between 10 and 25% of the total weight of the formulation, a trifunctional acrylate monomer preferably forming between 5 and 20% of the total weight of the composition, and a monofunctional acrylate monomer preferably forming between 5 and 15% of the total weight of the composition.

10. A manufacturing process according to any one of the preceding claims, characterized in that the organic polymer matrix and / or the masking coating is alkali-sensitive.

11. A manufacturing process according to any one of the preceding claims, characterized in that the organic polymer matrix and / or the coating is soluble and / or dispersible in a liquid, for example an aqueous solution, having a pH equal to or greater than 9.

12. A manufacturing process according to any one of the preceding claims, characterized in that the organic polymer matrix forms between 20 and 80% of the total weight of the composition.

13. A manufacturing process according to any one of the preceding claims, characterized in that the composition further comprises one or more solvents, said solvent(s) forming between 15 and 80% of the total weight of the composition, preferably between 20 and 75% of the total weight of the composition, for example between 30 and 60% of the total weight of the composition.

14. A manufacturing process according to the preceding claim, characterized in that said solvent(s) comprise at least one or more of the following compounds: isopropanol, butanol, methoxypropanol, ethyl acetate, butyl acetate, cyclohexane, 2-butoxyethanol acetate, 2-methoxy-1-methylethyl acetate, propylene carbonate, isopropyl myristate, diethylene glycol monoethyl ether acetate, glycerol, heavy naphtha, hexane, and / or methylcyclohexane. A manufacturing process according to claim 13 or 14, characterized in that said solvent(s) comprise at least water. A manufacturing process according to any one of the preceding claims, characterized in that it is free of metallic and / or electrically conductive particles. A manufacturing process according to any one of the preceding claims, characterized in that the coating is electrically insulating and / or dielectric. A manufacturing process according to any one of the preceding claims, characterized in that the composition further comprises at least one dispersed organic or inorganic solid, said solid preferably being formed by powdered particles dispersed within the other constituents of said composition. A manufacturing process according to the preceding claim, characterized in that said solid comprises a mineral filler, an organic filler, and / or a fibrous filler.A manufacturing process according to claim 18 or 19, characterized in that said solid comprises at least one or more of the following compounds: silica, calcium carbonate, barium sulfate, aluminum hydroxide, and / or a wax. A manufacturing process according to any one of claims 18 to 20, characterized in that said solid forms between 0.5% and 50%, preferably between 1% and 40%, more preferably between 1.5% and 30%, more preferably still between 2% and 20%, of the total weight of the composition. A manufacturing process according to any one of the preceding claims, characterized in that the composition comprises at least one cationic or anionic radical photoinitiator capable of crosslinking at least a portion of the polymer matrix when the composition is subjected to ultraviolet light.

23. A coating manufacturing process according to the preceding claim, characterized in that the photoinitiating agent forms between 0.5% and 15%, preferably between 1% and 10%, more preferably between 1% and 7%, of the total weight of the composition.

24. A method for manufacturing the coating of claim 22 or 23, characterized in that the photoinitiating agent comprises at least one of the following compounds: benzophenone, 1-hydroxycyclohexylphenyl ketone, dimethylhydroxyacetophenone, diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide, 1-chloro-4-propoxythioxanthone, 2,2-dimethoxy-1,2-phenylacetophenone.

25. A manufacturing process according to any one of the preceding claims, characterized in that the composition comprises at least one or more of the following additional compounds: rheology agent, wetting agent, antifoaming agent, dispersant, surfactant, stabilizer, colorant, synergistic amine.

26. Manufacturing process according to the preceding claim, characterized in that the additional compound(s) form between 0.01% and 10% of the total weight of the composition.

27. A manufacturing process according to any one of the preceding claims, characterized in that the masking coating has a glass transition temperature and / or a melting temperature lower than the glass transition temperature of the substrate.

28. A manufacturing process according to any one of the preceding claims, characterized in that said deposition step is carried out at least in part by screen printing and / or by direct printing.

29. A manufacturing method according to any one of the preceding claims, characterized in that the masking coating has a thickness of between 1 pm and 20 pm, preferably between 3 pm and 10 pm.

30. A manufacturing method according to any one of the preceding claims, characterized in that the masking coating has at least a first portion and a second portion, distinct from each other, the thickness of the first portion being different from the thickness of the second portion.

31. A manufacturing process according to any one of the preceding claims, characterized in that during said thermoforming step, the surface of the substrate thus covered by the masking coating is deformed.

32. A manufacturing process according to any one of the preceding claims, characterized in that the thermoforming step is carried out before the metallization step.

33. A method according to any one of claims 1 to 31, characterized in that the thermoforming step is carried out after the metallization step.

34. A manufacturing process according to any one of the preceding claims, characterized in that the thermoforming step is carried out before the elimination step.

35. A method according to any one of the preceding claims characterized in that the metallic deposit is made of solid metal.

36. A process according to any one of the preceding claims, characterized in that the metallic deposit has, at the end of the metallization step, 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.

Images