Photoluminescent metal timepiece component
A watch component is manufactured via powder metallurgy with a mixture of metallic, photoluminescent, and glass powders, addressing the issue of inhomogeneous luminescence in existing designs by achieving a metallic appearance with uniform luminance.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- THE SWATCH GRP RES & DEVELONMENT LTD
- Filing Date
- 2025-10-29
- Publication Date
- 2026-06-25
Smart Images
Figure EP2025081245_25062026_PF_FP_ABST
Abstract
Description
P7340WQ01 / ML PHOTOLUMINESCENT METAL WATCHMAKING COMPONENT Technical field of the invention
[0001] The invention relates to an article, in particular a watch component, metallic photoluminescent. Technological background
[0002] There are various solutions for producing phosphorescent metal parts. For example, prior art has proposed phosphorescent aluminum parts made using a technology based on the use of aluminum foams impregnated with polymer resin loaded with photoluminescent pigments such as europium- and dysprosium-doped strontium aluminate (Eu). 2+ , Dy 3+(B: SrAl2O4). The disadvantage of such a design is that the luminescence is inhomogeneous and selectively present in areas where the part is not metallic. For aesthetic reasons, watch brands prefer an entirely metallic part that is luminescent and has a homogeneous luminance. Summary of the invention
[0003] The invention aims to produce a watch component in a metallic alloy with a homogeneous photoluminescent effect.
[0004] To this end, it is proposed to use powder metallurgy to produce said watch component from a mixture of three types of powders including a metallic powder, a glass powder to conduct light and a powder of photoluminescent pigments.
[0005] More specifically, the invention relates to a photoluminescent metallic watch component produced by powder metallurgy from a suitable material comprising a mixture: - of at least one metallic powder M, - of at least one photoluminescent pigment powder P, - of a powder of glass particles G and / or glass fibers G with said glass transparent to the UVA and visible spectra, - of one or more organic binders.
[0006] It also relates to the process using this material. More specifically, it relates to a process for manufacturing a photoluminescent metallic watch component comprising a metallic matrix with a dispersion of particles and / or glass fibers and photoluminescent pigments, the process comprising the steps of: - shaping of the aforementioned material, described above, to obtain a green piece, - Mixing and sintering of the green piece to obtain a rough draft of the photoluminescent metallic watch component, - finishing treatment on at least one face of the blank of the photoluminescent metallic watch component to make the photoluminescent pigments P and the glass particles and / or fibers G appear on the surface of said face.
[0007] It also relates to a photoluminescent metallic watch component comprising a metallic matrix M with a dispersion of glass particles and / or fibers G and photoluminescent pigments P, with photoluminescent pigments P and glass particles and / or fibers G present on the surface on at least one face of the watch component.
[0008] The watch component, and in particular the watch component made with the aforementioned material, retains its metallic appearance while being phosphorescent. The pigments are dispersed within the material with glass particles or fibers that conduct light to the surface, thus ensuring a homogeneous phosphorescent effect. Brief description of the figure
[0009] Figure 1 schematically represents on the left the mixture of powders and binders within the green part and on the right the photoluminescent metallic alloy obtained after debinding and sintering. Detailed description of the invention
[0010] The invention relates to a photoluminescent metallic watch component obtained by powder metallurgy. More specifically, it may be a casing component chosen from the non-exhaustive list including a case, case back, bezel, bracelet link, bracelet, pin buckle, clasp, dial, hands, and dial markers. It may also be a movement component such as an oscillating weight.
[0011] The watch component is manufactured using powder metallurgy, starting with a mixture of powders and a binder. A minimum of three powders are required. As shown schematically on the left of Figure 1, there is a metallic powder 1, a photoluminescent pigment powder 2, and a glass powder 3 in the form of spherical particles or glass fibers. The example illustrates three powders, but the mixture could include several metallic powders, several types of pigments, glass in the form of particles and / or fibers, and possibly an additive.
[0012] Metal powder can be made from any metal alloy, such as iron or titanium alloys. A key characteristic of metal powder is that the average particle size (D50) measured by laser particle size analysis according to ISO 13320:2020 is less than or equal to 15 µm. Powder with this particle size distribution is obtained, for example, by atomization.
[0013] The photoluminescent pigment is preferably an alkaline earth aluminate derivative of the type M(x)Al(y)O(z) with M=Ba, Sr, Ca doped with rare earths. More specifically, the pigment can be aluminate of Europium-doped strontium, Dysprosium with the formula Sr(x)Al(y)O(z): Eu 2+ ,Dy 3+ In particular, it could be SRAI14O25: Eu 2+ ,Dy 3+ or even SrAl2O4: Eu 2+ ,Dy 3+Both pigments may be present. The pigments have an average diameter D50 of 80 microns or less, preferably 15 microns or less. Preferably, the pigments are encapsulated in a mineral shell, transparent to UVA and visible light, to protect them from the moisture to which they will be exposed during use on the final product. This could, for example, be a silica (SiC₂) shell obtained via a sol-gel process. Above the mineral shell, the pigments are advantageously coated with a SiU₂ or parylene F layer by PECVD (Plasma-Enhanced Chemical Vapor Deposition) to further enhance the seal.
[0014] Glass particles or fibers are also transparent to the UVA and visible spectra, i.e., in the wavelength range of 315 nm to 750 nm. They can be any type of glass, including, for example, silica or borosilicate glass. Glass particles have an average diameter D50, measured by laser particle size analysis according to ISO 13320:2020, of between 80 µm and 1 mm, and fibers have a diameter of between 20 µm and 50 µm and a length of between 200 µm and 1 mm.
[0015] Within the powder mixture, the powders are present in the following proportions by weight. The metallic powder M is present in a mass fraction greater than 1 / 5, i.e., M > 1 / 5. The pigment powder P is present in a mass fraction between 1 / 3 and 2 / 3, inclusive, i.e., 1 / 3 < P < 2 / 3. The glass particles and / or fibers G are present in a mass fraction between 2 / 15 and 7 / 15, inclusive, i.e., 2 / 15 < G < 7 / 15.
[0016] This powder mixture is then bound with an organic matrix. For the entire mixture comprising the powders and organic binders, the mass percentage of powders is greater than 95% and the mass percentage of the organic binder(s) is less than or equal to 5%. The binder The organic binder can be of the PVA (polyvinyl alcohol) type. It can also be a mixture of organic binders such as polyolefins and paraffins.
[0017] The powders can be pre-mixed with the organic binder(s). For example, the powders are mixed in a ball mill. Then, the powder mixture is dispersed into the organic matrix using a high-speed mixer or a twin-screw extruder. Alternatively, the powders and organic binders are mixed simultaneously in the high-speed mixer or twin-screw extruder.
[0018] The resulting material is shaped using various processes known to those skilled in the art, such as pressing, 3D screen printing, 3D printing, and injection molding. The molded part, also called the green part and referenced as 6 in Figure 1 on the left, is then debinded and subsequently sintered to obtain the watch component with the correct dimensions. Debinding is achieved through thermal degradation and / or dissolution in a solvent. Sintering is then carried out at a temperature that depends on the metal alloy. For example, for a Ti alloy (Ti-6Al-4V) shaped by injection molding, sintering is performed at a temperature between 1100 and 1500°C, preferably between 1200 and 1350°C, for a time between 1 and 10 hours, preferably between 2 and 6 hours, under an inert atmosphere.We thus obtain, as schematically shown on the right of figure 1, a watch component 7 with a metallic matrix 1 in which the pigments 2 and the glass particles or fibers 3 are dispersed.
[0019] Next, the watch component undergoes a finishing treatment to reveal the pigments and glass particles or fibers on at least one of its faces, thus achieving the final luminescent properties. Preferably, this finishing treatment is electropolishing, which erodes the metal to expose the glass particles or fibers and pigments on the surface.
[0020] In the final watch component, the organic binders have been dissolved or burned. Only traces of these binders may remain. Therefore, we can consider that within the watch component, relative to the total weight, the metallic matrix M, the photoluminescent pigments P, and the glass particles or fibers G follow the same mass fraction relationships as before: - M > 1 / 5, - 1 / 3 < P < 2 / 3, - 2 / 15 < G < 7 / 15.
[0021] In the presence of a mineral shell on the pigments and possibly a coating on the shells, the percentage of the compounds relating thereto are integrated into the percentage P.
Claims
DEMANDS 1. Photoluminescent metallic watch component (7) comprising a metallic matrix M (1 ) with a dispersion of particles (3) and / or glass fibers G and photoluminescent pigments P (2), with on at least one face of the watch component (7) photoluminescent pigments P (2) and particles and / or glass fibers G (3) present on the surface.
2. Photoluminescent metallic watch component (7) according to claim 1, characterized in that the mass fractions of the metallic matrix M (1), of the glass particles and / or fibers G (3) and of the photoluminescent pigments P (2) respond to the following relationships with respect to the total weight: - M > 1 / 5, - 1 / 3 < P < 2 / 3, - 2 / 15 < G < 7 / 15.
3. Photoluminescent metallic watch component (7) according to claim 1 or 2, characterized in that the photoluminescent pigments P (2) are rare earth doped alkaline-earth aluminate derivatives.
4. Photoluminescent metallic watch component (7) according to the preceding claim, characterized in that the photoluminescent pigments P (2) are Europium, Dysprosium doped alkaline earth aluminate derivatives of formula Sr(x)Al(y)O(z): Eu 2+ ,Dy 3+ .
5. Photoluminescent metallic watch component (7) according to claim 3 or 4, characterized in that the photoluminescent pigments P (2) are Sr4Al4O25: Eu 2+ ,Dy 3+ and / or SrAI2O4: Eu 2+ ,Dy 3 .
6. Photoluminescent metallic watch component (7) according to any one of claims 3 to 5, characterized in that the photoluminescent pigments P (2) have an average diameter D50 less than or equal to 80 pm, preferably less than or equal to 15 pm.
7. Photoluminescent metallic watch component (7) according to any one of claims 3 to 6, characterized in that the photoluminescent pigments P (2) are encapsulated in a mineral shell transparent to the UVA and visible spectra.
8. Photoluminescent metallic watch component (7) according to the preceding claim, characterized in that the mineral shell is coated with a layer of SiC or parylene F.
9. Photoluminescent metallic watch component (7) according to any one of claims 1 to 8, characterized in that the glass powder particles G (3) have an average diameter D50 between 80 pm and 1 mm and in that the glass fibers G have a diameter between 20 pm and 50 pm and a length between 200 pm and 1 mm.
10. A method for producing a photoluminescent metallic watch component (7) comprising a metallic matrix (1) with a dispersion of glass particles and / or fibers (3) and photoluminescent pigments P (2), the method comprising the steps of: - shaping of a metallic matrix M (1 ) with a dispersion of particles (3) and / or glass fibers G and photoluminescent pigments P (2), with on at least one face of the watch component (7) photoluminescent pigments P (2) and particles and / or glass fibers G (3) present on the surface, to obtain a green part (6), - debinding and sintering of the green part (6) to obtain a rough draft of the photoluminescent metallic watch component (7), - finishing treatment on at least one face of the blank of the photoluminescent metallic watch component (7) to make the photoluminescent pigments P (2) and the glass particles and / or fibers G (3) appear on the surface of said face.
11. A method according to the preceding claim, characterized in that the finishing treatment is electropolishing.