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JP-7856734-B2 - A method for depositing a coating on a substrate that at least partially covers visible light.

JP7856734B2JP 7856734 B2JP7856734 B2JP 7856734B2JP-7856734-B2

Inventors

  • ニコラ・フランソワ
  • ナタリー・テレス

Assignees

  • ザ・スウォッチ・グループ・リサーチ・アンド・ディベロップメント・リミテッド

Dates

Publication Date
20260511
Application Date
20241209
Priority Date
20231220

Claims (12)

  1. A method (100) for depositing a coating (20) that at least partially absorbs visible light onto a substrate (1) in order to form an article (10) such as a component of a timer, wherein the method (100) The first step (110) is to prepare the base material (1), A second step (120) involves depositing a first liquid mixture comprising a binder, a solvent, and a pigment having a particle size distribution d90 value of 20 to 120 nm , thereby depositing a first layer (21) that covers at least a portion of the substrate (1) and is formed by the evaporation of the solvent. A third step (130) involves depositing a second liquid mixture comprising a binder, a solvent, and a pigment whose particle size distribution d90 value is greater than that of the pigment in the first layer (21), thereby depositing a second layer (22) that covers a first portion of the first layer (21) and is formed by the evaporation of the solvent. The fourth step (140) includes depositing a third liquid mixture comprising a binder, a solvent, and a pigment whose d90 particle size distribution value is greater than the d90 particle size distribution value of the pigment in the second layer (22) , thereby depositing a third layer (23) formed by evaporation of the solvent, which covers a second portion of the first layer (21) that is different from the first portion covered by the second layer (22) , The pigment in the first layer (21) is a carbon black pigment. A method characterized by (100).
  2. The method according to 1 (100), characterized in that a third step (130) for depositing a second layer (22) and/or a fourth step (140) for depositing a third layer (23) includes a substep of placing a selectivity 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.
  3. The method according to claim 1 (100), characterized in that the first liquid mixture forming the first layer (21) of the coating (20) contains 5 to 10% by weight of a pigment.
  4. The method according to 1 (100), characterized in that the second liquid mixture forming the second layer (22) contains 4 to 10% by weight of a pigment.
  5. The method according to 1 (100), characterized in that the third liquid mixture forming the third layer (23) contains 1 to 5% by weight of a pigment.
  6. The method according to 1 (100), further comprising a fifth step (150) of depositing a fourth liquid mixture comprising a binder, a solvent, and a pigment whose d90 value of particle size distribution is greater than the d90 value of the pigment particle size distribution in the third layer (23), thereby depositing a fourth layer (24) which covers the third portion of the first layer (21) that is different from the first portion covered by the second layer (22) and the second portion covered by the third layer (23), and which is formed by the evaporation of the solvent.
  7. The method according to 6 (100), characterized in that the fourth liquid mixture forming the fourth layer (24) contains 0.5 to 5% by weight of a pigment.
  8. The method according to 1 (100), characterized in that each of the layers (21, 22, 23, 24) of the coating (20) is deposited by sputtering, spraying, dipping, screen printing, printing or pad printing.
  9. The method according to 1 (100), characterized in that each of the liquid mixtures deposited to form each of the layers (21, 22, 23, 24) of the coating (20) comprises a binder, a solvent, a pigment, and optionally a matting agent, glass beads , and/or a dispersant.
  10. The method according to 9 (100), characterized in that the binder is a polymer.
  11. The method according to 10 (100), characterized in that the binder is acrylic, epoxy polymer, or polyurethane.
  12. The method according to claim 1 (100), characterized in that each of the liquid mixtures deposited to form each of the layers (21, 22, 23, 24) of the coating (20) is a colored ink.

Description

This invention relates to the field of surface treatment for articles such as decorative items and components of timekeeping devices. This invention relates, in particular, to a method for depositing a decorative coating having optical properties that absorb visible light. The present invention further relates to articles covered with a decorative coating that absorbs visible light, such as components of a timekeeping device. The present invention has particularly interesting applications in the field of portable clocks, for the decoration of components used in articles and timepieces. Such articles and components include, for example, plates, cocks, gear trains, screws, oscillating weights, dials, indices, decorations, aperture discs, hands, or any other components of a timepiece movement or external components. There is a coating that absorbs visible light and has a light absorption rate exceeding 99.8%. In particular, a carbon nanotube-based Vantablack® coating is known, in which the nanotubes are oriented perpendicular to the substrate surface and pressed together. Such a coating provides a black color with an absorption coefficient of 99.965% in visible light. However, carbon nanotube-based coatings are extremely expensive and pose health risks because such particles are known to be carcinogenic, mutagenic, or reproductively toxic. Musou® acrylic paint, known for its ease of use and application, possesses a maximum absorption rate of 99.4% for visible light and a luminance component L* close to 10. However, this coating is extremely fragile; even a light touch can easily cause peeling or a decrease in absorption. For example, if dust or fibers accumulate, it is very difficult to clean this type of coating without compromising its aesthetic appearance. Such paints are not readily usable in industries such as the portable watch industry. As a result, there is a need to improve such visible light-absorbing coatings so that they can be used on items, such as components of timekeeping devices, without health risks and without the risk of the coating being damaged by simple contact or handling of the item. A schematic cross-sectional view of an article, such as a component for a timer, is shown, comprising a substrate and a coating that at least partially absorbs visible light according to the present invention.The present invention illustrates some key sequential steps in an implementation example of a method for producing an article such as a timekeeping component by depositing a coating on a substrate that at least partially absorbs visible light.This shows one exemplary embodiment of an article according to the present invention. In this specification, the colorimetric properties of the light-absorbing coating obtained according to the coating deposition method of the present invention are expressed in the CIE L*a*b* color space and are measured on a polished sample using a KONICA MINOLTA CM-3610-A spectrophotometer, according to the CIE 1976 standard, using the following parameters: CIE D65 illumination source (daylight 6500K), 10° tilt, SCI measurement (including specular reflection), and a measurement area with a diameter of 4 mm. The CIELAB color space (compliant with CIE standard No. 15, ISO 7724/1, DIN 5033 Teil 7, and ASTM E-1164) includes a luminance component L*, which represents the light reflectivity of a material. In addition to L*, there are also the a* component (green/red) and the b* component (blue/yellow). In this application, particle and pigment sizes 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 used are smaller than their d90 value. Figure 1 schematically shows a cross-sectional view of an article 10, such as a timekeeping device component, which includes a base material 1 and a decorative coating 20 having the property of absorbing visible light. The coating 20 covers at least a portion of the substrate 1. Such a coating 20 according to the present invention forms a non-homogeneous structure composed of multiple regions with varying roughness, where different regions of the coating contain pigments with different particle sizes. Preferably, the density of the pigment between different regions of the coating 20 also changes such that it decreases as the size of the pigment increases. For example, article 10 is a component of a timepiece that does not reflect light, has a luminance component L* of less than 20, and is intended to give the impression of a deep, high-intensity color. For instance, it could be a timepiece movement, or an external component of a timepiece, such as a plate, cock, bridge, wheel, screw, oscillating weight, dial, index, decoration, aperture disc, hands, or any other component or member. Figure 3 shows a timer 200 including article 10 according to the present invention. In this exemplary embodiment, article 10 acc