Method for depositing coating on substrate, which coating at least partially absorbs visible light

Abstract

To provide a method for depositing a coating with at least locally high light absorption on a substrate while avoiding the use of carbon nanotubes and / or graphene particles.SOLUTION: There is provided a method for depositing a coating 20 on a substrate 1, the method comprising: a first step of supplying a substrate; a second step of depositing a first layer 21 formed by depositing a first liquid mixture comprising a binder, a solvent and pigments with a d90 value of nanometric dimension to cover at least a portion of the substrate through evaporation of the solvent; a third step of depositing a second layer 22 formed by depositing a second liquid mixture comprising pigments with a d90 value greater than that of the pigments in the first layer to cover a first portion of the first layer; a fourth step of depositing a third layer 23 formed by depositing a third liquid mixture comprising pigments with a d90 value greater than that of the pigments in the second layer to cover a second portion of the first layer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to the field of surface treatment of articles such as components of ornaments and timepieces.

[0002] In particular, the present invention relates to a method for depositing a decorative coating having optical properties that absorb visible light.

[0003] The present invention further relates to an article coated with a decorative coating that absorbs visible light as described above, such as a component of a timepiece.

[0004] The present invention has particularly interesting applications in the field of portable timepieces for the decoration of components used in articles and timepieces. Such articles and components include, for example, plates, cocks, gear trains, screws, pendulums, dials, indices, decorations, aperture disks, hands, or any other arbitrary components of the movement and outer components of a timepiece.

Background Art

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

[0006] In particular, a carbon nanotube-based Vantablack (registered trademark) coating that is oriented perpendicular to the surface of the substrate and pressed against each other is known. Such a coating gives a black color having an absorption coefficient of 99.965% in visible light.

[0007] However, carbon nanotube-based coatings are very expensive and pose health risks. This is because such particles are known to have carcinogenic, mutagenic, or reproductive toxicity.

[0008] The Musou (registered trademark) acrylic paint, which is easy to use and apply, has a light absorption rate of up to 99.4% for visible light and a luminance component L* close to 10. However, this coating has the characteristic of being very fragile, and it is easy for the coating to peel off or the absorption rate to decrease just by lightly touching the coating. For example, when dust or fibers are deposited, it is very difficult to clean this type of coating without damaging its aesthetic appearance. Such paints are not easily available in the portable watch industry, etc.

[0009] As a result, it is necessary to improve such visible light-absorbing coatings so that they can be handled without any health risks and without the risk of damage to the coating due to simple contact or handling of the article. For example, they can be used for components of timepieces.

Summary of the Invention

Problems to be Solved by the Invention

[0010] In view of such a situation, an object of the present invention is to provide an article including a coating having at least locally a high light absorption rate while avoiding the use of carbon nanotubes and / or graphene particles.

Means for Solving the Problems

[0011] For this purpose, the present invention relates to a method of depositing a coating that at least partially absorbs visible light on a substrate to form an article such as a component of a timepiece. This method includes: a first step of preparing a substrate; a second step of depositing a first liquid mixture including a binder, a solvent, and a pigment having a d90 value in the nanometer level dimension to cover at least a part of the substrate and depositing a first layer formed by evaporation of the solvent; A third step of depositing a second layer that covers a first portion of the first layer and is formed by evaporation of the solvent by depositing a second liquid mixture including a binder, a solvent, and a pigment having a d90 value greater than the d90 value of the pigment in the first layer. A fourth step of depositing a third layer that covers a second portion of the first layer and is formed by evaporation of the solvent by depositing a third liquid mixture including a binder, a solvent, and a pigment having a d90 value greater than the d90 value of the pigment in the second layer.

[0012] One object of the present invention is to provide a method for depositing a decorative coating having different levels of visible light absorbency, which is easy to implement the deposition and can produce a decorative coating with a luminance component L* of less than 20 using various substrates.

[0013] Preferably, the second step of depositing the second layer and / or the third step of depositing the third layer includes a sub-step of disposing a selective mask on the first layer so as to select at least a part of the first layer to be covered before depositing the corresponding liquid mixture.

[0014] Preferably, the first liquid mixture forming the first layer of the coating contains 5 to 10% by weight of a pigment.

[0015] Preferably, the second liquid mixture forming the second layer and the third liquid mixture forming the third layer each contain 4 to 10% by weight, preferably 4 to 8% by weight, of a pigment, and 1 to 5% by weight, preferably 1 to 4% by weight, of a pigment.

[0016] Preferably, the deposition method further includes depositing a fourth liquid mixture including a binder, a solvent, and a pigment having a d90 value greater than the d90 value of the pigment in the third layer, to cover a third portion of the first layer, which is different from the first portion covered by the second layer and different from the second portion covered by the third layer, and depositing a fourth layer formed by evaporation of the solvent.

[0017] Preferably, the fourth liquid mixture for forming the fourth layer contains 0.5 to 5% by weight, preferably 0.5 to 4% by weight, more preferably 0.5 to 1% by weight, of the pigment.

[0018] Preferably, some of the layers of the coating are deposited by sputtering, spraying, dipping, screen printing, printing or pad printing.

[0019] Preferably, some of the liquid mixtures deposited to form some of the layers of the coating contain a binder, a solvent, and a pigment, and further optionally contain a matting agent, glass beads, and / or a dispersant.

[0020] Preferably, the binder is a polymer.

[0021] Preferably, the binder is made of acrylic, epoxy polymer or polyurethane.

[0022] Preferably, some of the liquid mixtures deposited to form some of the layers of the coating are colored inks.

[0023] The present invention further relates to an article including a substrate and a coating deposited by the method according to the present invention.

[0024] Therefore, such an article includes a light-absorbing surface coating having a luminance component L* of less than 20.

[0025] Preferably, the article is a component of a timepiece.

[0026] The present invention further relates to a timepiece including such a component of a timepiece.

[0027] The objects, advantages and features of the present invention can be further understood by reading the following detailed description with reference to the drawings.

Brief Description of the Drawings

[0028]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0029] In this specification, the colorimetric properties of the light-absorbing coating obtained according to the method of depositing the coating according to the present invention are represented using the CIE L*a*b* color space, and for the polished sample, measured according to the CIE 1976 standard using a KONICA MINOLTA CM-3610-A spectrophotometer with the following parameters. That is, the illumination source is CIE D65 (daylight 6500K), 10° inclination, SCI measurement (including specular reflection), and the measurement area is 4 mm in diameter.

[0030] The CIELAB color space (conforming to CIE Standard No. 15, ISO 7724 / 1, DIN 5033 Teil 7, ASTM E-1164) has a luminance component L* representing the light reflectivity of the material, which is luminance, and in addition, an a* component that is a green / red component and a b* component that is a blue / yellow component.

[0031] In the present application, the sizes of the particles and the pigments are characterized in relation to the d90 value of the particle size distribution. In the particle size distribution, the use of the d90 value means that at least 90% of the particles or pigments in the total particles used are smaller than the d90 value.

[0032] Figure 1 schematically shows a cross-sectional view of an article 10, such as a component of a timepiece, including a substrate 1 and a decorative coating 20 having the property of absorbing visible light.

[0033] The coating 20 covers at least a part of the substrate 1. Such a coating 20 according to the present invention forms a non-uniform structure composed of a plurality of regions with different roughnesses, and different regions of this coating contain pigments with different particle sizes.

[0034] Preferably, the density of the pigments between the various regions of the coating 20 also varies, preferably decreasing as the size of the pigments increases.

[0035] As an example, the article 10 does not reflect light, has a luminance component L* of less than 20, and is intended to give an impression of a deep and intense color, such as a component of a timepiece, for example, a movement for a timepiece, or a plate, cock, bridge, wheel, screw, pendulum, dial, index, decoration, aperture disk, hand, or any other component or member of an outer component of a timepiece.

[0036] Figure 3 shows a timepiece 200 including the article 10 according to the present invention. In this exemplary embodiment, the article 10 according to the present invention is a dial.

[0037] The substrate 1 can have any property and can be made of, for example, metal, polymer, ceramics, or composite material.

[0038] The method according to the present invention can be used to obtain an article 10 comprising a coating 20 having a luminance component L* of less than 20 using various substrates. In comparison, coating methods using physical vapor deposition (PVD) cannot be used to create a coating having a luminance component L* of less than 20 due to the topology of the deposited layer. In the case of PVD, the luminance component L* of the matte coating is 25 - 30.

[0039] Thanks to the specific multi-region structure of the coating 20 according to the present invention, it becomes possible to create patterns by varying different levels of visible light absorption. Preferably, thanks to the multi-region structure of the coating 20 according to the present invention, it becomes possible to create monochromatic patterns having different levels of visible light absorption.

[0040] The coating 20 includes a first layer 21 that forms a base layer configured to cover the substrate 1 over at least a part of the substrate 1.

[0041] Preferably, the first layer 21 completely covers at least one surface of the substrate 1.

[0042] This first layer 21 has a thickness sufficient to ensure that the underlying layer 21 is homogeneous and opaque and that optical disturbances from the substrate 1 are inactive. For example, the first layer 21 has a thickness of 1 μm or more and less than 20 μm, and more preferably has a thickness of 5 μm - 10 μm.

[0043] Preferably, the first layer 21 is formed by depositing a first liquid mixture containing a binder, a pigment, and a solvent on the substrate 1.

[0044] For example, this underlying layer is formed by depositing a first liquid mixture containing 30 - 40 wt% binder, 50 - 60 wt% solvent, and 5 - 10 wt% pigment.

[0045] For example, this underlayer is formed by depositing a first liquid mixture comprising 30% by weight of an acrylic binder, 60% by weight of a solvent, and 10% by weight of Emperor (registered trademark) 1600 carbon black pigment.

[0046] Optionally, the first liquid mixture can further contain a matting agent, such as nanosilica, to further enhance the strength of the coating 20.

[0047] Optionally, the first liquid mixture can further contain a dispersant that contributes to suspending the pigment in the liquid mixture.

[0048] Preferably, the binder in the first liquid mixture forming the first layer 21 is made of a polymer, such as acrylic, epoxy polymer or polyurethane.

[0049] For example, the first liquid mixture is a colored ink.

[0050] For example, the first liquid mixture is a black ink containing carbon black pigment.

[0051] The first liquid mixture is applied to the substrate 1, for example, by sputtering, spraying, dipping, screen printing, printing or pad printing.

[0052] When the liquid mixture is applied to the substrate 1, the solvent evaporates and the binder shrinks around the pigment, thereby forming the first layer 21 of the coating 20.

[0053] Preferably, the pigment in the first layer 21 has a d90 value that is on the nanometer level of dimension, for example, 20 - 120 nm, preferably less than 100 nm. Thus, the underlayer 21 is a homogeneous layer with low roughness.

[0054] The multi-region structure of the coating 20 is formed by a plurality of juxtaposed layers each covering a predetermined portion of the first layer 21.

[0055] As shown in FIG. 1, the first layer 21 is covered by the second layer 22 at a first predetermined portion of the first layer 21. The pigment contained in the second layer has a d90 value greater than the d90 value of the pigment in the first layer 21.

[0056] The first layer 21 is further covered by a third layer 23 at a second predetermined portion of the first layer 21, and this second portion is different from the first portion covered by the second layer 22. This second portion may be arranged side by side with the first portion, or may not be arranged side by side.

[0057] The pigment contained in the third layer 23 has a d90 value greater than the d90 value of the pigment in the second layer 22.

[0058] The first layer 21 can also be covered by other layers at various specific portions of the first layer 21, thereby creating a specific pattern in which the light absorption level varies according to the size of the pigment having a specific optical characteristic.

[0059] For the sake of explanation, in the exemplary embodiment shown in FIG. 1, there is a fourth layer 24 locally deposited on the first layer 21 at a predetermined third portion. This third portion is different from the first portion covered by the second layer 22 and is also different from the second portion covered by the third layer 23. This third portion can be arranged to be aligned with the first portion and / or the second portion. These various layers deposited on the first layer 21 do not overlap each other.

[0060] The pigment contained in the fourth layer 24 has a d90 value greater than the d90 value of the pigment in the third layer 23.

[0061] As an example, the pigments in the layers 22, 23, 24 covering the first layer 21 have dimensions at the micrometer level.

[0062] As an example, the pigment contained in the second layer 22 has a d90 value that is on the order of micrometers, less than 20 μm, for example, on the order of 15 μm.

[0063] As an example, the pigment contained in the third layer 23 has a d90 value that is from 20 to 100 μm, preferably on the order of 80 μm.

[0064] As an example, the pigment contained in the fourth layer 24 has a d90 value that is from 100 to 300 μm, preferably on the order of 250 μm.

[0065] Each of the layers 22, 23, 24 that partially covers the first layer 21 is formed by depositing a liquid mixture through one or more masks deposited on the first layer 21 to mask specific regions and expose other regions intended to receive layers having a predetermined particle size.

[0066] Each of the layers 22, 23, 24 that partially covers the first layer 21 is formed by depositing a liquid mixture containing a binder, a solvent, and a pigment, and the d90 values of the pigments in those different liquid mixtures vary among the different layers.

[0067] Each of the layers 22, 23, 24 that partially covers the first layer 21 is formed by depositing the liquid mixture by sputtering, spraying, dipping, screen printing, printing, or pad printing.

[0068] After each mixture is deposited on the first layer 21, the solvent evaporates, enabling the binder to polymerize and shrink around the pigment, thereby forming various layers having different particle sizes.

[0069] Preferably, the properties of the binder, pigment, and solvent used to form the liquid mixtures for depositing the various layers 22, 23, 24 are the same.

[0070] Optionally, the liquid mixture for forming the various layers of the coating 20 can include a matting agent, such as nanosilica, to further enhance the strength of the coating 20.

[0071] Optionally, the liquid mixture used to form the various layers of the coating 20 can include a dispersant that contributes to suspending the pigment in the first liquid mixture.

[0072] Optionally, the liquid mixture used to form the laminate 25 can include glass spheres to further increase the roughness of the laminate.

[0073] Preferably, the binder in the liquid mixture for forming the various layers of the coating 20 is made of a polymer, such as acrylic, epoxy polymer or polyurethane.

[0074] For example, the liquid mixture for forming the various layers of the coating 20 is a colored ink, such as a black ink containing carbon black as a pigment.

[0075] Preferably, the properties of the binder, pigment and solvent used to form the various layers of the coating 20 are the same.

[0076] However, the pigments used to form the various layers of the coating 20 can have different properties between the various layers and compared to the pigments used to form the first layer 21.

[0077] Preferably, the pigment content in the liquid mixture for forming the various layers 22, 23, 24 deposited on the first layer 21 is 5 to 10% by weight. Preferably, the pigment content in the liquid mixture is higher as the d90 value of the pigment is smaller.

[0078] For example, the second layer 22 is made from a liquid mixture containing 4 to 10% by weight, preferably 4 to 8% by weight, of pigment.

[0079] For example, the third layer 23 is made from a liquid mixture containing 1 to 5% by weight, preferably 1 to 4% by weight, of pigment.

[0080] For example, the fourth layer 24 is made from a liquid mixture containing 0.5 to 4% by weight, preferably 0.5 to 1% by weight, of pigment.

[0081] Figure 2 shows some of the main steps in a method 100 for depositing a coating 20 that at least partially absorbs visible light on a substrate 1 according to the present invention.

[0082] The deposition method 100 according to the present invention includes a first step 110 of preparing a substrate 1.

[0083] The deposition method 100 according to the present invention includes a second step 120 of depositing a first layer 21, called a base layer, that covers at least a part of the substrate 1. This second deposition step 120 is performed by sputtering, spraying, dipping, screen printing, printing, or pad printing of a first liquid mixture containing a binder, a solvent, and 5 to 10% by weight of a pigment having a d90 value in the nanometer level, for example, less than 100 nm.

[0084] The step 120 of depositing this first layer 21 includes sub-steps of evaporating the solvent from the liquid mixture applied to the substrate 1 and contracting the binder around the pigment to form the first layer 21 of the coating 20.

[0085] This deposition method 100 further includes a third step 130 of depositing a second layer 22 that covers a first portion of the previously deposited first layer 21. The particle size of this second layer 22 is different from that of the first layer 21. In particular, the pigment contained in this second layer has a d90 value that is larger than the d90 value of the pigment in the first layer 21.

[0086] This second layer 22 is deposited by sputtering, spraying, dipping, screen printing, printing, or pad printing of a second liquid mixture containing a binder, a solvent, and 4 to 10% by weight of a pigment.

[0087] Preferably, the second liquid mixture for depositing the second layer 22 contains 4 to 8% by weight of pigment.

[0088] This third step 130 includes a first sub-step of placing a mask on the first layer 21 so as to select the area of the first layer 21 covered by the second layer 22.

[0089] This third step 130 includes a second sub-step of selectively evaporating the solvent from the second liquid mixture applied to the first layer 21, contracting the binder around the pigment, and forming the second layer 21 of the coating 20 on the first layer 21.

[0090] This deposition method 100 further includes a fourth step 140 of depositing a third layer 23 that covers a second portion of the first layer 21, which is a portion different from the first portion selected to receive the second layer 22. The third layer 23 has a particle size different from that of the second layer 22. In particular, the pigment contained in this third layer 23 has a d90 value greater than the d90 value of the pigment in the second layer 22.

[0091] Also, this third layer 23 is deposited by sputtering, spraying, dipping, screen printing, printing or pad printing of a third liquid mixture containing a binder, a solvent, and 1 to 5% by weight of pigment.

[0092] Preferably, the third liquid mixture for depositing the third layer 23 contains 1 to 4% by weight of pigment.

[0093] This fourth step 140 includes a first sub-step of placing a mask on the first layer 21 so as to select the area of the first layer 21 covered by the third layer 23.

[0094] This fourth step 140 includes a second sub-step of selectively evaporating the solvent from the third liquid mixture applied to the first layer 21, contracting the binder around the pigment, and forming the third layer 23 of the coating 20 on the first layer 21.

[0095] As illustrated by way of example, this deposition method 100 further includes a fifth step 140 of depositing a fourth layer 24 that covers a third portion of the first layer 21, which is a portion different from the previously selected first portion so as to receive the second layer 22 and the third layer 23. The fourth layer 24 has a particle size different from that of the third layer 23. In particular, the pigment contained in this fourth layer 24 has a d90 value greater than the d90 value of the pigment in the second layer 22.

[0096] Also, this fourth layer 24 is deposited by sputtering, spraying, dipping, screen printing, printing or pad printing of a fourth liquid mixture containing a binder, a solvent, and 0.5 to 5 wt% of a pigment.

[0097] Preferably, the fourth liquid mixture for depositing the fourth layer 24 contains 0.5 to 4 wt% of a pigment.

[0098] This fifth step 150 includes a first sub-step of placing a mask on the first layer 21 so as to select a region of the first layer 21 covered by the fourth layer 24.

[0099] This fifth step 150 includes a second sub-step of selectively evaporating the solvent from the fourth liquid mixture applied to the first layer 21 to contract the binder around the pigment and form the fourth layer 24 of the coating 20 on the first layer 21.

[0100] Naturally, this deposition method 100 can include other steps of depositing additional layers according to the desired pattern and properties of the coating 20.

[0101] According to a first exemplary embodiment of the present invention, a brass substrate is used, for example, to form a watch face, and the light-absorbing coating according to the present invention is applied thereto.

[0102] The thickness of this brass substrate is, for example, 0.27 mm.

[0103] The first layer 21 is applied onto the brass substrate by immersing it in a first 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.

[0104] The second layer 22 is applied onto the first layer 21 through a first selective mask by immersing it in a second liquid mixture consisting of 2 g of polyurethane resin (Berlacryl), 0.3 g of Emperor 1600 carbon black pigment, and 3.5 g of Berlaflex diluent. This layer is dried for 20 minutes to evaporate the diluent.

[0105] The third layer 23 is applied onto the first layer 21 through a second selective mask by immersing it in a third liquid mixture consisting of 2 g of polyurethane resin (Berlacryl), 0.2 g of Norit A ultra E153 pigment, and 4 g of Berlaflex diluent. This layer is dried for 20 minutes to evaporate the diluent.

[0106] The fourth layer 24 is applied onto the first layer 21 through a third selective mask by immersing it in a fourth liquid mixture consisting of 2 g of polyurethane resin (Berlacryl), 0.2 g of Norit SX super E153 pigment, 1.5 g of glass spheres with a size of 90 - 150 μm, and 4 g of Berlaflex diluent. This layer is dried for 20 minutes to evaporate the diluent.

[0107] Such coating results in a black surface coating and a brass dial with a luminance component L* of 16.

Explanation of Reference Numerals

[0108] 1 Substrate 10 Article 20 Coating 21 First layer 22 Second layer 23 Third layer 24 Fourth layer 200 Timer

Claims

1. A method (100) for depositing a coating (20) that at least partially absorbs visible light onto a substrate (1) to form an article (10), such as a component of a timepiece, said method (100) comprising: a first step (110) of providing a substrate (1); a second step (120) of depositing a first liquid mixture comprising a binder, a solvent and a pigment having a particle size distribution with a d90 value between 20 and 120 nm, thereby depositing a first layer (21) covering at least a portion of the substrate (1) and formed by evaporation of the solvent; a third step (130) of depositing a second liquid mixture comprising a binder, a solvent and a pigment having a particle size distribution d90 value greater than the particle size distribution d90 value of the pigment in the first layer (21) to deposit a second layer (22) covering a first portion of the first layer (21) and formed by evaporation of the solvent; a fourth step (140) of depositing a third liquid mixture comprising a binder, a solvent and a pigment having a particle size distribution d90 value greater than the particle size distribution d90 value of the pigment in the second layer (22) to deposit a third layer (23) covering a second portion of the first layer (21) different from the first portion covered by the second layer (22) and formed by evaporation of the solvent; The pigment in the first layer (21) is a carbon black pigment. A method (100) comprising:

2. The third step (130) of depositing the second layer (22) and / or the fourth step (140) of depositing the third layer (23) comprise the sub-step of placing a selective mask on the first layer (21) to select at least a portion of the first layer (21) to be covered before depositing the corresponding liquid mixture.

2. The method (100) of claim 1 .

3. The first liquid mixture forming the first layer (21) of the coating (20) contains 5 to 10% by weight of a pigment.

2. The method (100) of claim 1 .

4. The second liquid mixture forming the second layer (22) contains 4 to 10% by weight of a pigment.

2. The method (100) of claim 1 .

5. The third liquid mixture forming the third layer (23) contains 1 to 5% by weight of a pigment.

2. The method (100) of claim 1 .

6. The method further comprises a fifth step (150) of depositing a fourth liquid mixture comprising a binder, a solvent, and a pigment having a particle size distribution d90 value greater than the particle size distribution d90 value of the pigment in the third layer (23), to cover a third portion of the first layer (21), the fourth portion being different from the first portion covered by the second layer (22) and different from the second portion covered by the third layer (23), the fourth layer (24) being formed by evaporation of the solvent.

2. The method (100) of claim 1 .

7. The fourth liquid mixture forming the fourth layer (24) contains 0.5 to 5% by weight of a pigment.

7. The method (100) of claim 6.

8. Each of the layers (21, 22, 23, 24) of the coating (20) is deposited by sputtering, spraying, dipping, screen printing, printing or pad printing.

2. The method (100) of claim 1 .

9. Each of the liquid mixtures deposited to form each of the layers (21, 22, 23, 24) of the coating (20) includes a binder, a solvent, a pigment, and optionally a matting agent, glass beads, and / or a dispersant.

2. The method (100) of claim 1 .

10. The binder is a polymer 10. The method (100) of claim 9.

11. The binder is an acrylic, an epoxy polymer, or a polyurethane.

11. The method (100) of claim 10.

12. Each of the liquid mixtures deposited to form each of the layers (21, 22, 23, 24) of the coating (20) is a colored ink.

2. The method (100) of claim 1 .

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