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EP-4741925-A1 - METHOD FOR PRODUCING A COMPONENT HAVING A MICROSTRUCTURE PATTERN ON A COLOURED RESIN AND COMPONENT OBTAINED BY SAID METHOD

EP4741925A1EP 4741925 A1EP4741925 A1EP 4741925A1EP-4741925-A1

Abstract

This disclosure relates to a method for manufacturing a component featuring a microstructure pattern on a colored resin, comprising: provide a printing mold (30) comprising a mold pattern (32) including structural elements having a micrometric and/or nanometric size dimension; provide a substrate (10) and form a layer of coloured resin (20) on a substrate (10), the resin comprising at least one colouring agent; to replicate on the resin layer (20) a replicated pattern (22) corresponding to the negative of the mold pattern (32), including the application of the printing mold (30) against the resin layer (20); and crosslink the resin (20) so as to produce a hardened resin having the replicated pattern (22). The mold pattern (32) includes structural elements having an average lateral dimension between 1 nm and 5000 µm, and an aspect ratio between the height of the structural elements and the average lateral dimension between approximately 0.1 and 2.

Inventors

  • BLONDIAUX, NICOLAS
  • Pugin, Raphaël

Assignees

  • CSEM Centre Suisse d'Electronique et de Microtechnique SA - Recherche et Développement

Dates

Publication Date
20260513
Application Date
20241112

Claims (17)

  1. A method for manufacturing a component having a microstructure pattern on a colored resin, comprising: provide a printing mold (30) comprising a mold pattern (32) including structural elements having a micrometric and/or nanometric size dimension; provide a substrate (10) and form a layer of coloured resin (20) on the substrate (10), the resin (20) comprising at least one colouring agent; to replicate on the resin layer (20) a replicated pattern (22) corresponding to the negative of the mold pattern (32), including the application of the printing mold (30) against the resin layer (20); and crosslink the resin (20) so as to produce a hardened resin having the replicated pattern (22); in which the mold pattern (32) comprises structural elements having an average lateral dimension between 1 nm and 5000 µm, and an aspect ratio between the height of the structural elements and the average lateral dimension between about 0.1 and 10.
  2. The method according to claim 1, wherein the mold pattern (32) may include structural elements having an average lateral dimension between 1 nm and 100 µm or between 10 µm and 500 µm, and an aspect ratio between the height of the structural elements and the average lateral dimension between about 0.1 and 10.
  3. The method according to claim 1 or 2, in which the resin (20) is a photocurable resin; and in which crosslinking the resin is achieved by irradiation with UV illumination (40).
  4. The method according to claim 1 or 2, wherein the resin (20) is a thermosetting resin; and in which crosslinking the resin is achieved by heating the resin to a crosslinking temperature ( TR ) of 20 to 200°C.
  5. The method according to any one of claims 1 to 4, including further a step of separating the resin (20), crosslinked and comprising the replicated pattern (22), from the printing mold (30).
  6. The method according to any one of claims 2 to 5, in which the irradiance of UV radiation (40) is between 10 and 500 mW/cm 2 in order to take into account the presence of the pigment in the resin (20) and the thickness of the resin layer (20).
  7. The method according to any one of claims 2 to 6, in which the printing mold (30) comprises a glass or polymer transparent to the emission spectrum of UV illumination (40).
  8. The method according to any one of claims 1 to 7, in which the colored resin layer (20) has a thickness between 10 µm and 500 µm.
  9. The method according to any one of claims 1 to 8, in which, during the replication step, the distance between the printing mold (30) and the upper surface (11) of the substrate (10) is controlled so as to have a minimum thickness (d), corresponding to the thickness of the resin layer (20) at the level of the deepest hollow of the replicated pattern (22), so as to obtain the desired coloring.
  10. The method according to any one of claims 1 to 9, in which the coloring agent comprises at least one pigment, in particular an inorganic pigment.
  11. The method according to claim 10, in which the refractive index of the pigment is between 1.5 and 1.6.
  12. The method according to claim 10 or 11, in which the resin 20 comprises from about 1% by weight to about 10% by weight, relative to the total weight of the resin dispersion (20), of at least one pigment in dispersion in the resin.
  13. The method according to any one of claims 1 to 12, in which the mold pattern (32) includes inclined structures configured so that the replicated pattern (22) produces a color gradient effect caused by a thickness gradient of the resin layer (20) resulting from the replicated pattern (22).
  14. The method according to any one of claims 1 to 13, including further a step of covering the resin layer (20) with the replicated pattern (22) with an additional layer (60) in order to adjust the reflectivity of the surface of the component.
  15. The method according to any one of claims 1 to 14, in which the mold pattern (32) includes a guilloché pattern, Geneva stripes, anglage, soleillage, or colimaçonnage.
  16. The method according to any one of claims 1 to 15, in which the component includes a watch component, a jewelry component, a micromechanical component, a security and/or anti-counterfeiting element, or a decorative component.
  17. The method according to claim 16, in which the component includes a watch dial.

Description

technical field This disclosure relates to the manufacture of a component featuring a microstructure pattern on a colored resin. Specifically, the component may include a watch component, a jewelry component, a micromechanical component, a security and/or anti-counterfeiting element, or a decorative component. In particular, this disclosure relates to the manufacture of a watch dial featuring such a microstructure pattern. State of the art Colored lacquers or thin film stacks produced by PVD/ALD are commonly used to control the color of watch dials. While thin film stacks can be as thin as a few hundred nanometers to a few micrometers, a considerable thickness, up to 100 micrometers, is required for lacquers. In practice, only thin film stacks can be used to accurately cover a guilloché or machined pattern or surface textures (sunburst, sandblasting, shot peening, etc.) that have ridges with lateral dimensions of a few micrometers to a few millimeters and depths of a few tens of micrometers, thus imparting color while preserving the decorative optical effect provided by the machined pattern. Applying a lacquer to such patterns results in a loss of pattern sharpness and a degradation of the optical effect produced by the guilloché or machined design. Furthermore, although the color palette for thin film stacks is constantly improving, each color requires a A specific design is required to achieve the correct Pantone color and avoid color shifts when the viewing angle changes. Furthermore, the final effect is difficult to predict on textured surfaces. Certain colors, such as warm red, are also difficult to achieve using thin-film deposition techniques. The document CH709669A1 This describes the use of a combination of a partially reflective PVD layer with a thin ALD layer to obtain a range of interference colors from browns, magenta, blue, yellow, orange, violet, green, and pink, depending on the thickness of the ALD layer. The underlying PVD layer allows for modulation of the color brightness. To overcome the angular dependence, it is possible to introduce surface roughness beneath the stack of thin films (see, for example, Bläsi, T. Kroyer, TE Kuhn and O. Höhn, "The MorphoColor Concept for Colored Photovoltaic Modules," in IEEE Journal of Photovoltaics, vol. 11, no. 5, pp. 1305-1311, 2021 From an industrial point of view, the thickness of the layers depends on the specific surface area of the parts to be treated, which can lead to problems of reproducibility or flexibility when processing structured/textured parts. Other examples of vacuum-deposited layer stacking exist that produce optical effects without angular dependence. For example, it is possible to deposit colored layers by PVD based on metal oxides or, more generally, semi-absorbent and transparent dielectric layers. This approach is used in the document EP2392689A1 to achieve a specific red color. To do this, an iron oxide film is deposited by PVD and combined with a transparent layer. Other coloring methods are possible, such as the production of colloidal glass. The resulting effect is very attractive because it is free from angular dependence, but the color palette remains limited. (see for example, S. Magkiriadou, J. Park, YS Kim, and VN Manoharan·On the Absence of Red Structural Color in Photonic Glasses, Bird Feathers and Certain Beetles, Phys. Rev. E 90, 062302 . Disclosure Summary This disclosure relates to a method for manufacturing a component featuring a microstructure pattern on a colored resin, comprising: provide a printing mold comprising a mold pattern including structural elements having a dimension of micrometric and/or nanometric size; provide a substrate and form a layer of colored resin on a substrate, the resin comprising at least one coloring agent; to replicate on the resin layer a pattern corresponding to the negative of the mold pattern, including applying the printing mold against the resin layer; and crosslink the resin to produce a hardened resin with the replicated pattern. The mold pattern includes structural elements having an average lateral dimension between 1 nm and 5000 µm, and an aspect ratio between the height of the structural elements and the average lateral dimension between 0 and 10, for example between 0.1 and 10, between 0.5 and 5, or between 0.5 and 2. The component may include a watch component, a jewelry component, a micromechanical component, a security and/or anti-counterfeiting element, or a decorative component. This disclosure further relates to a watch dial obtained by the process and comprising such a microstructure pattern. Brief description of the figures Examples of implementation of the invention are shown in the description illustrated by the accompanying figures, in which: there figure 1 shows a layer of resin formed on a substrate and a printing mold comprising a mold pattern; according to one embodiment; there figure 2 shows a replication step comprising the application of a structure