Method of depositing visible light absorbing coating on substrate

Abstract

One aspect of the invention relates to a method (100) of depositing a visible light absorbing coating (20) on a substrate (1) to form an article (10), such as a timepiece component, said deposition method (100) being characterized in that it comprises: a first step (110) of providing a substrate (1); a second step (120) of depositing a bottom layer (21) covering at least a portion of the substrate (1) by applying a first liquid mixture comprising a binder, a solvent and a pigment having a d90 percentile of nano-size, the bottom layer (21) being formed by evaporating the solvent; a third step (130) of depositing a stack (25) of a plurality of layers (22, 23, 24) of different particle sizes between each layer n of the stack (25) by continuously applying a plurality of liquid mixtures comprising a binder, a solvent and a pigment of different particle sizes; each layer of the stack (25) is formed by evaporating the solvent, and each layer n at least partially covers the previous layer n-1.

Description

Field of the Invention

[0001] The field of the invention relates to the surface treatment of articles, such as decorative articles or watch components.

[0002] The invention more particularly relates to a method for depositing a decorative coating having optical properties of absorbing visible light.

[0003] The invention also relates to an article coated with such a decorative coating that absorbs visible light, such as a watch component.

[0004] The invention has a particularly interesting application in the field of horology for decorating articles or components used in watches, such as plates, bridges, trains, screws, oscillating weights, dials, indexes, appliques, aperture discs, hands or any other component of a watch movement or case. Background Art

[0005] There are coatings that absorb visible light and have a light absorption rate of more than 99.8%.

[0006] We particularly know coatings based on carbon nanotubes oriented perpendicular to the surface of the substrate and pressed against each other. Such coatings provide a black color with a visible light absorption coefficient of 99.965%.

[0007] However, coatings based on carbon nanotubes are very expensive and pose health risks because these particles are known to be carcinogenic, mutagenic or reprotoxic.

[0008] Acrylic paints that are easier to use and apply are also known and have a visible light absorption rate of up to 99.4% and a brightness component L* close to 10. However, this coating has the particularity of being very fragile, and slight contact with the coating can easily cause peeling of the coating or deterioration of its absorption rate. For example, if dust or fibers are deposited, it is very complicated to clean this type of coating without damaging its appearance. Such paints are not easily applicable to, for example, the watchmaking industry.

[0009] Therefore, there is a need to improve these coatings that absorb visible light so that they can be used on articles that can be processed, such as watch components, without health risks and without the risk of damage to the coating due to simple contact or handling of the article. Summary of the Invention

[0010] In this context, the present invention aims to provide an article comprising a coating having a very high light absorption rate while avoiding the use of carbon nanotubes and / or graphene particles.

[0011] To this end, the present invention relates to a method for depositing a visible light absorbing coating on a substrate to form an article such as a clock assembly, the deposition method being characterized in that it comprises:

[0012] - a first step of providing a substrate;

[0013] - a second step of depositing an underlayer covering at least a part of the substrate by applying a first liquid mixture, the first liquid mixture comprising a binder, a solvent, and a pigment having a d90 percentile in the nanoscale, the underlayer being formed by evaporating the solvent;

[0014] - a third step of depositing a stack of multiple layers having different particle sizes between each layer n of the stack by continuously applying multiple liquid mixtures, the liquid mixtures comprising a binder, a solvent, and pigments having different particle sizes; each layer of the stack is formed by evaporating the solvent, and each layer n at least partially covers the previous layer n - 1.

[0015] According to the present invention, one of the objects of the present invention is to provide a method for depositing a decorative coating that absorbs visible light, is easy to implement, and can obtain a surface coating having a brightness component L* of less than 20 on various substrates.

[0016] Preferably, the first liquid mixture for forming the underlayer of the coating comprises 5 to 10% by weight of the pigment.

[0017] Preferably, the third step of depositing the stack of multiple layers is carried out by continuously applying multiple liquid mixtures, and each liquid mixture for forming the multiple layers of the stack comprises a binder, a solvent, and a pigment, and the d90 percentile of the pigment increases between each successive deposition of the layers forming the stack.

[0018] Preferably, each layer (n) of the multiple layers of the stack has a pigment with a d90 percentile of its particle size corresponding to n*k / 10 μm, where k is a homothetic factor between the d90 percentiles of the pigments of two successive layers of the stack.

[0019] Preferably, the third step of depositing the stack of multiple layers is carried out by continuously applying multiple liquid mixtures, and each liquid mixture for forming the multiple layers of the stack comprises a binder, a solvent, and a pigment, and the d90 percentile of the size of the pigment increases between each successive deposition of the layers of the stack, and as the d90 percentile of the pigment increases, the weight proportion of the pigment in each liquid mixture decreases.

[0020] Preferably, the various liquid mixtures for forming the plurality of layers of the stack contain 0.5 to 10% by weight of pigment.

[0021] Preferably, the third step of depositing the stack includes a first sub-step of depositing a first layer of the stack from a liquid mixture, the liquid mixture containing 0.5 to 10% by weight of pigment in the mixture, the pigment having a d90 percentile corresponding to k / 10 μm, where k is a similarity factor between the d90 percentiles of the pigment in two consecutive layers of the stack.

[0022] Preferably, the liquid mixture for depositing the first layer of the stack contains 4 to 10% by weight of pigment, preferably 4 to 8% by weight of pigment.

[0023] Preferably, the third step of depositing the stack includes a second sub-step of depositing a second layer of the stack from a liquid mixture, the liquid mixture containing 0.5 to 10% by weight of pigment in the mixture, the pigment having a d90 percentile corresponding to 2k / 10 μm, where k is a similarity factor between the d90 percentiles of the pigment in two consecutive layers of the stack.

[0024] Preferably, the liquid mixture for depositing the second layer of the stack contains 1 to 4% by weight of pigment.

[0025] Preferably, the third step of depositing the stack includes a third sub-step of depositing a third layer of the stack from a liquid mixture, the liquid mixture containing 0.5 to 10% by weight of pigment in the mixture, the pigment having a d90 percentile corresponding to 3k / 10 μm, where k is a similarity factor between the d90 percentiles of the pigment in two consecutive layers of the stack.

[0026] Preferably, the liquid mixture for depositing the third layer of the stack contains 0.5 to 4% by weight of pigment, preferably 0.5 to 1% by weight of pigment.

[0027] Preferably, the bottom layer and / or the plurality of layers of the stack are deposited by spraying, dipping, screen printing, printing or pad printing.

[0028] Preferably, the first liquid mixture for forming the bottom layer of the coating and / or the various liquid mixtures for forming the plurality of layers of the stack are composed of a binder, a solvent, a pigment, an optional matting agent, glass beads and / or a dispersant.

[0029] Preferably, the binder is a polymer.

[0030] Preferably, the binder is acrylic, an epoxy polymer or polyurethane.

[0031] Preferably, the first liquid mixture forming the bottom layer of the coating and / or the various liquid mixtures forming the multiple layers of the stack are colored inks.

[0032] The present invention also relates to an article comprising a substrate and a coating applied by the method according to the present invention.

[0033] Such articles thus have a light-absorbing surface coating with a brightness component L* of less than 20.

[0034] Preferably, the article is a clock component.

[0035] The present invention also relates to a clock comprising such a clock component. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The objects, advantages and features of the present invention will become apparent upon reading the following detailed description with reference to the following drawings:

[0037] - Figure 1 A cross-sectional view schematically showing an article, such as a clock component, comprising a substrate and a coating that absorbs visible light according to the present invention;

[0038] - Figure 2 Shows the main successive steps of an example of a method for depositing a coating that absorbs visible light on a substrate to manufacture an article such as a clock component according to the present invention;

[0039] - Figure 3 Shows an embodiment of an article according to the present invention. DETAILED DESCRIPTION

[0040] In this specification, the chromaticity properties of the light-absorbing coatings obtained by the method of depositing coatings according to the present invention are represented using the CIE L*a*b* chromaticity space and measured on polished samples using a KONICA MINOLTA CM-3610-A spectrophotometer with the following parameters according to the CIE 1976 standard: illumination light source CIE D65 (daylight 6,500°K), 10° inclination, SCI measurement (including specular reflection), measurement area diameter 4 mm.

[0041] The CIELAB color space (according to CIE standard no. 15, ISO 7724 / 1, DIN 5033 Teil 7, ASTM E-1164) has a brightness component L*, which represents the way the material reflects light and is assimilated to brightness, as well as an a* component as the green / red component and a b* component as the blue / yellow component.

[0042] In the present application, the sizes of the particles and pigments are characterized relative to the d90 value of the particle size distribution. In the particle size distribution, the use of the d90 percentile means that in the set of particles used, at least 90% of the particles or pigments have a size below a given d90 value.

[0043] Figure 1 A cross-sectional view of an article 10, such as a clock assembly, is schematically shown, which includes a substrate 1 and a visible light-absorbing coating 20 covering at least a portion of the substrate 1 by a deposition method 100 according to the present invention. Such a light-absorbing coating 20 according to the present invention forms a multi-layer structure composed of pigments, and the particle sizes of the pigments are unequal between the layers, preferably increasing with the increase in the number of layers.

[0044] Preferably, the pigment density between different layers of the coating 20 is also variable, preferably decreasing with the increase in the number of layers.

[0045] The article 10 is, for example, a clock assembly, such as a motherboard, a bridge plate, a wheel, a screw, a balance weight, a dial, a time scale, a lettering block, a window disc, a pointer, or any other component or part (organ) of a clock movement or a component of a clock case, and it is desired to endow it with a deep and strong color impression without light reflection, and the brightness component L* is less than 20.

[0046] Figure 3 A clock 200 including the article 10 according to the present invention is shown. In this embodiment, the article 10 according to the present invention is a dial.

[0047] The substrate 1 can be any material, such as metal, polymer, ceramic, or even composite material.

[0048] Due to the method according to the present invention, articles 10 with a coating 20 having a brightness component L* less than 20 can be obtained with various substrates. For comparison, physical vapor deposition (PVD) coating methods cannot have a coating with a brightness component L* less than 20 due to the topology of the deposited layer. In the case of PVD, the brightness component L* of a matte coating is 25 to 30.

[0049] The specific multi-layer structure of the light-absorbing coating 20 according to the present invention can avoid the reflection phenomenon on the visible surface of the coating. The coating 20 also allows light to diffuse into the structure generated by the particle size difference of the pigments constituting the coating until it is captured, thereby obtaining the maximum light absorption rate.

[0050] The coating 20 includes a bottom layer 21 forming a base layer, which is configured to cover the substrate 1 at least on a part of the substrate 1.

[0051] Preferably, the bottom layer 21 completely covers at least one surface of the substrate 1.

[0052] The underlying layer 21 has a thickness sufficient to ensure its uniformity and opacity and that the optical interference of the substrate 1 no longer has an effect. For example, the underlying layer 21 has a thickness equal to or greater than 1 μm and less than 20 μm, and more preferably a thickness of 5 μm to 10 μm.

[0053] Preferably, the underlying layer 21 is formed by depositing a first liquid mixture comprising an adhesive, a pigment, and a solvent on the substrate 1.

[0054] For example, the underlying layer is formed by depositing a first liquid mixture which comprises, by weight, 30% to 40% of an adhesive, 50% to 60% of a solvent, and 5% to 10% of a pigment.

[0055] For example, the underlying layer is formed by depositing a first liquid mixture which consists, by weight, of 30% acrylic adhesive, 60% solvent, and 10% carbon black pigment 1600.

[0056] Optionally, the first liquid mixture may further comprise a matting agent, such as nano-silica, to further enhance the strength of the coating 20.

[0057] Optionally, the first liquid mixture may further comprise a dispersant to assist in suspending the pigment in the liquid mixture.

[0058] Preferably, the adhesive of the first liquid mixture for forming the underlying layer 21 is a polymer, such as acrylic, epoxy polymer, or polyurethane.

[0059] For example, the first liquid mixture is a colored ink.

[0060] For example, the first liquid mixture is a black ink containing carbon black pigment.

[0061] For example, the first liquid mixture is applied to the substrate 1 by spraying, dipping, screen printing, printing, or pad printing.

[0062] Once the liquid mixture has been applied to the substrate 1, the solvent evaporates and the adhesive shrinks around the pigment, thereby producing the underlying layer 21 of the coating 20.

[0063] Preferably, the pigment in the underlying layer 21 has a nano-size, for example, a d90 percentile of 20 to 120 nm, preferably less than 100 nm. In this way, the underlying layer 21 is a uniform layer with low roughness.

[0064] The underlying layer 21 is covered by a stack 25 of a number of layers 22, 23, 24 superposed on one another, and each layer of the stack 25 has a pigment with a d90 percentile different from the pigment size in the layer it covers.

[0065] Preferably, the stack 25 has pigments distributed according to the d90 percentile increasing from the substrate towards the surface of the coating 20. In this way, each layer of the stack 25 has a pigment with a d90 percentile greater than the d90 percentile of the pigment in the layer it covers.

[0066] Preferably, each layer n of the stack 25 has a pigment with a d90 percentile equal to n*k / 10 μm, where k is the similarity factor between the d90 percentile of the pigment in the previously deposited layer (n - 1) and the d90 percentile of the pigment in the layer n to be deposited (i.e., between two consecutive layers of the stack 25).

[0067] Preferably, the similarity factor is from 5 to 1,000.

[0068] In the embodiment shown in Figure 1 the stack 25 includes three consecutive layers 22, 23, 24. Of course, the stack 25 may include at least two consecutive layers or more than three consecutive layers to form a specific structure of the stack 25 covering the underlying layer 21.

[0069] The first layer 22 of the stack 25 contains a pigment with a d90 percentile size greater than the d90 percentile of the pigment in the underlying layer 21, for example, being in the micron size and less than 20 μm, preferably in the range of 15 μm.

[0070] The second layer 23 of the stack 25 that at least partially covers the first layer 22 of the stack 25 contains a pigment with a d90 percentile, for example, in the range of 80 μm. The third layer 24 of the stack 25 that at least partially covers the second layer 23 of the stack 25 contains a pigment with a d90 percentile, for example, in the range of 250 μm.

[0071] Each of the layers 22, 23, 24 is formed by continuously depositing a liquid mixture containing a binder, a pigment, and a solvent. The d90 percentile of the pigment in the different liquid mixtures varies according to the above ratio to form different layers with an increased particle size, thereby increasing the roughness of each deposited layer compared to the previous layer.

[0072] After each mixture is applied by spraying, dipping, screen printing, printing, or pad printing, the solvent evaporates to allow the binder around the pigment to polymerize and shrink, thereby forming a solid layer that at least partially covers the previous layer or the underlying layer 21. The new layer has a roughness greater than the previous layer.

[0073] Preferably, the binder, pigment properties, and solvent used to form the liquid mixtures for depositing the respective layers 22, 23, 24 of the stack 25 are the same.

[0074] Optionally, the liquid mixture for forming the stack 25 may include a matting agent, such as nano-silica, to further enhance the strength of the stack 25 and, more generally, the strength of the coating 20.

[0075] Optionally, the liquid mixture for forming the stack 25 may include a dispersant to help suspend the pigments in the first liquid mixture.

[0076] Optionally, the liquid mixture for forming the stack 25 may include glass beads to further increase the roughness of the stack. Preferably, the glass beads are used in the last layer of the stack 25.

[0077] Preferably, the binder of the liquid mixture for forming the stack 25 is a polymer, such as acrylic, epoxy polymer or polyurethane.

[0078] For example, the liquid mixture for forming the stack 25 is a colored ink.

[0079] Preferably, the binder and solvent of the layers for forming the stack 25 are the same as those for manufacturing the underlying layer 21. The pigments of the layers for forming the stack 25 may be the same as or different from the pigments for manufacturing the underlying layer 21.

[0080] Preferably, the proportion of the pigment in the liquid mixtures of the different layers 22, 23, 24 forming the stack 25 is from 0.5 wt% to 10 wt%. Preferably, when the d90 percentile of the pigment is small, the proportion of the pigment in the liquid mixture is high. Thus, the density of the pigment in the layers 22, 23, 24 of the stack 25 becomes lower and lower as the d90 percentile of the pigment increases.

[0081] For example, the first layer 22 of the stack 25 is made of a liquid mixture containing 4 to 10 wt% of the pigment, preferably 4 to 8 wt% of the pigment.

[0082] For example, the second layer 23 of the stack 25 is made of a liquid mixture containing 1 to 4 wt% of the pigment.

[0083] For example, the third layer 24 of the stack 25 is made of a liquid mixture containing 0.5 to 4 wt%, preferably 0.5 to 1 wt% of the pigment.

[0084] Figure 2 The main steps in the method 100 for depositing a coating 20 that absorbs visible light on a substrate 1 according to the present invention are shown.

[0085] The deposition method 100 according to the present invention includes a first step 110 of providing a substrate 1.

[0086] The deposition method 100 according to the present invention includes a second step 120 of depositing a bottom layer 21 or a base layer covering at least a part of the substrate 1. This second deposition step 120 is carried out by spraying, dipping, screen printing, printing or pad printing a first liquid mixture, which contains a binder, a solvent and 5 to 10% by weight of pigments having a d90 percentile in the nanoscale (e.g., less than 100 nm).

[0087] This step 120 of depositing the bottom layer 21 includes a sub-step of evaporating the solvent from the liquid mixture applied to the substrate 1, such that the binder shrinks around the pigments to form the bottom layer 21 of the coating 20.

[0088] The deposition method 100 further includes a third step 130 of depositing a stack 25 of a plurality of superimposed layers 22, 23, 24 having different particle sizes between each layer of the stack 25.

[0089] This third step 130 includes a first sub-step 131 of depositing the first layer 22 of the stack 25 by a liquid mixture, which contains a binder, a solvent and 0.5 to 10% by weight of pigments having a d90 percentile higher than 100 nm and equal to k / 10 μm, where k is a similarity factor between the d90 percentiles of the pigments of two consecutive layers of the stack 25.

[0090] Preferably, the liquid mixture for depositing the first layer 22 contains 4 to 10% by weight of pigments.

[0091] Preferably, the liquid mixture for depositing the first layer 22 contains 4 to 8% by weight of pigments.

[0092] This first sub-step 131 is carried out by spraying, dipping, screen printing, printing or pad printing.

[0093] This first sub-step 131 includes a step of evaporating the solvent from the liquid mixture applied to the bottom layer 21, such that the binder shrinks around the pigments to form the first layer 22 of the coating 20 superimposed on the bottom layer 21.

[0094] This third step 130 includes a second sub-step 132 of depositing the second layer 23 of the stack 25 by a liquid mixture, which contains a binder, a solvent and 0.5 to 10% by weight of pigments having a d90 percentile equal to 2k / 10 μm, where k is a similarity factor between the d90 percentile of the pigments of the first layer 22 and the d90 percentile of the pigments of the second layer 23.

[0095] Preferably, the liquid mixture for depositing the second layer 23 contains 1 to 4% by weight of pigments.

[0096] This second sub-step 132 is carried out by spraying, dipping, screen printing, printing or pad printing.

[0097] This second sub-step 132 includes the step of evaporating the solvent from the liquid mixture applied to the first layer 22, such that the binder shrinks around the pigment to form a second layer 23 of the coating 20 superposed on the first layer 22.

[0098] This third step 130 includes a third sub-step 133 of depositing a third layer 24 of the stack 25 from a liquid mixture comprising a binder, a solvent and a pigment with a d90 percentile equal to 3k / 10 μm, where k is a similarity factor between the d90 percentile of the pigment of the second layer 23 and the d90 percentile of the pigment of the third layer 24.

[0099] Preferably, the liquid mixture for depositing the third layer 24 comprises 0.5 to 4% by weight of the pigment.

[0100] Preferably, the liquid mixture for depositing the third layer 24 comprises 0.5 to 1% by weight of the pigment.

[0101] This third sub-step 133 is carried out by spraying, dipping, screen printing, printing or pad printing.

[0102] This third sub-step 133 includes the step of evaporating the solvent from the liquid mixture applied to the second layer 23, such that the binder shrinks around the pigment to form a third layer 24 of the coating 20 superposed on the second layer 23.

[0103] Of course, this deposition method 100 may include other sub-steps of depositing additional layers according to the number of layers required in the stack 25 of the coating 20.

[0104] According to a first example of the invention, a brass substrate is used, for example a watch dial on which is applied a light-absorbing coating according to the invention.

[0105] This brass substrate is for example 0.27 mm thick.

[0106] The bottom layer 21 is applied to the brass substrate by dipping in an initial liquid mixture consisting of 2 g of polyurethane resin (Berlacryl), 0.5 g of Emperor 1600 carbon black pigment and 2.8 g of Berlaflex diluent. This layer is dried for 20 minutes to evaporate the diluent.

[0107] The first layer 22 of the stack 25 is applied to the bottom layer 21 by dipping in a second liquid mixture consisting of 2 g of polyurethane resin (Berlacryl), 0.3 g of Living Ink pigment, and 3.5 g of Berlaflex thinner. The layer is dried for 20 minutes to evaporate the thinner.

[0108] The second layer 23 of the stack 25 is applied to the first layer 22 by dipping in a third liquid mixture consisting of 2 g of polyurethane resin (Berlacryl), 0.2 g of NoritA ultra E153 pigment, and 4 g of Berlaflex thinner. The layer is dried for 20 minutes to evaporate the thinner.

[0109] The third layer 24 of the stack 25 is applied to the second layer 23 by dipping in a fourth liquid mixture consisting of 2 g of polyurethane resin (Berlacryl), 0.2 g of NoritSX super E153 carbon pigment, 1.5 g of 90 - 150 μm glass beads, and 4 g of Berlaflex thinner. The layer is dried for 20 minutes to evaporate the thinner.

[0110] With such a coating, a brass dial with a black surface coating and a luminance component L* of 15.9 is obtained.

Claims

1. A method (100) for depositing a visible light absorbing coating (20) on a substrate (1) to form an article (10), the deposition method (100) being characterized in that it comprises: - a first step (110) of providing a substrate (1); - a second step (120) of depositing a bottom layer (21) covering at least a portion of the substrate (1) by applying a first liquid mixture comprising a binder, a solvent and a pigment having a nanometer-sized d90 percentile, said bottom layer (21) being formed by evaporating said solvent; - A third step (130) of depositing a stack (25) of multiple layers (22, 23, 24) having different particle sizes between each layer n of the stack (25) by successively applying a plurality of liquid mixtures, the liquid mixtures comprising a binder, a solvent and pigments having different particle sizes; each layer of the stack (25) is formed by evaporating the solvent and each layer n at least partially covers the previous layer n-1.

2. The method (100) for depositing a coating (20) that absorbs visible light onto a substrate (1) to form an article (10) according to claim 1, characterized in that The first liquid mixture forming the bottom layer (21) of the coating (20) contains 5 to 10% by weight of pigment.

3. A method (100) for depositing a coating (20) that absorbs visible light onto a substrate (1) to form an article (10) according to claim 1 or 2, characterized in that The third step (130) of depositing a stack (25) of multiple layers (22, 23, 24) is carried out by successively applying multiple liquid mixtures, each liquid mixture for forming the multiple layers (22, 23, 24) of the stack (25) comprising a binder, a solvent and a pigment, the d90 percentile of the pigment increasing between each consecutive deposition of a layer forming the stack (25).

4. A method (100) for depositing a coating (20) that absorbs visible light onto a substrate (1) to form an article (10) according to claim 1 or 2, characterized in that Each layer n of the plurality of layers (22, 23, 24) of the stack (25) has a pigment whose d90 percentile corresponds to n*k / 10 μm, where k is the similarity factor between the d90 percentiles of the pigments of two consecutive layers of the stack (25).

5. A method (100) for depositing a coating (20) that absorbs visible light onto a substrate (1) to form an article (10) according to claim 1 or 2, characterized in that The third step (130) of depositing a stack (25) of multiple layers (22, 23, 24) is carried out by successively applying multiple liquid mixtures, each liquid mixture for forming the multiple layers (22, 23, 24) of the stack (25) comprising a binder, a solvent and a pigment, the d90 percentile of the pigment increasing between each consecutive deposition of the layers of the stack (25), and as the d90 percentile of the pigment increases, the weight proportion of the pigment in each liquid mixture decreases.

6. The method (100) for depositing a coating (20) absorbing visible light on a substrate (1) to form an article (10) according to claim 5, characterized in that The liquid mixtures used to form the layers (22, 23, 24) of the stack (25) contain 0.5 to 10% by weight of pigment.

7. A method (100) for depositing a coating (20) that absorbs visible light onto a substrate (1) to form an article (10) according to claim 1 or 2, characterized in that The third step (130) of depositing the stack (25) comprises a first sub-step (131) of depositing a first layer (22) of the stack (25) from a liquid mixture, the liquid mixture comprising 0.5 to 10 weight % of a pigment in the mixture, the pigment having a d90 percentile corresponding to k / 10 μm, wherein k is a similarity factor between the d90 percentiles of the pigments of two consecutive layers of the stack (25).

8. The method (100) for depositing a coating (20) absorbing visible light on a substrate (1) to form an article (10) according to claim 7, characterized in that The liquid mixture used to deposit the first layer (22) of the stack (25) contains 4 to 10% by weight of pigment.

9. A method (100) for depositing a coating (20) that absorbs visible light onto a substrate (1) to form an article (10) according to claim 1 or 2, characterized in that The third step (130) of depositing the stack (25) comprises a second sub-step (132) of depositing a second layer (23) of the stack (25) from a liquid mixture, the liquid mixture comprising 0.5 to 10 weight % of a pigment in the mixture, the pigment having a d90 percentile corresponding to 2k / 10 μm, wherein k is a similarity factor between the d90 percentiles of the pigments of two consecutive layers of the stack (25).

10. The method (100) for depositing a coating (20) absorbing visible light on a substrate (1) to form an article (10) according to claim 9, characterized in that The liquid mixture used to deposit the second layer (23) of the stack (25) contains 1 to 4% by weight of pigment.

11. A method (100) for depositing a coating (20) that absorbs visible light onto a substrate (1) to form an article (10) according to claim 1 or 2, characterized in that The third step (130) of depositing the stack (25) includes a third sub-step (133) of depositing a third layer (24) of the stack (25) from a liquid mixture, wherein the liquid mixture contains 0.5 to 10 weight % of a pigment in the mixture, the pigment having a d90 percentile corresponding to 3k / 10 μm, where k is a similarity factor between the d90 percentiles of the pigments of two consecutive layers of the stack (25).

12. The method (100) for depositing a coating (20) absorbing visible light on a substrate (1) to form an article (10) according to claim 11, characterized in that The liquid mixture used to deposit the third layer (24) of the stack (25) contains 0.5 to 4% by weight of pigment.

13. A method (100) for depositing a coating (20) that absorbs visible light onto a substrate (1) to form an article (10) according to claim 1 or 2, characterized in that The base layer (21) and / or the plurality of layers (22, 23, 24) of the stack (25) are deposited by spraying, dipping, screen printing, printing or pad printing.

14. A method (100) for depositing a coating (20) that absorbs visible light onto a substrate (1) to form an article (10) according to claim 1 or 2, characterized in that The first liquid mixture forming the bottom layer (21) of the coating (20) and / or the plurality of liquid mixtures forming the plurality of layers (22, 23, 24) of the stack (25) consist of a binder, a solvent, a pigment, an optional matting agent, glass beads and / or a dispersant.

15. The method (100) for depositing a coating (20) absorbing visible light on a substrate (1) to form an article (10) according to claim 14, characterized in that The binder is a polymer.

16. The method (100) for depositing a coating (20) absorbing visible light on a substrate (1) to form an article (10) according to claim 15, characterized in that The adhesive is acrylic, epoxy polymer or polyurethane.

17. A method (100) for depositing a coating (20) that absorbs visible light onto a substrate (1) to form an article (10) according to claim 1 or 2, characterized in that The first liquid mixture forming the bottom layer (21) of the coating (20) and / or the plurality of liquid mixtures forming the plurality of layers (22, 23, 24) of the stack (25) are colored inks.

18. Article (10), characterized in that It comprises a substrate (1) and a light-absorbing coating (20) deposited by a deposition method according to one of claims 1 to 17, the coating (20) having a luminance component L* of less than 20.

19. The article (10) according to claim 18, characterized in that The article (10) is a timepiece component.

20. A timepiece (200) comprising a timepiece assembly (10) according to claim 19.

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