Transparent or translucent timepiece component with phosphorescent effect

Abstract

The invention relates to a timepiece component made from a transparent or translucent phosphorescent material, the material comprising between 95 and 99.5 wt% of a transparent thermoplastic or thermosetting resin, between 0.5 and 5 wt% of phosphorescent compounds, between 0 and 0.3 wt% of a porous silica, between 0 and 0.3 wt% of at least one optical brightener, and between 0 and 5 wt% of at least one dye and / or at least one additive.

Description

TRANSPARENT OR TRANSLUCENT WATCHMAKING COMPONENT WITH PHOSPHORESCENT EFFECT Technical field of the invention

[0001] The invention relates to a transparent or translucent watch component with a phosphorescent effect. In particular, the watch component may be a strap. Technological background

[0002] To date, transparent and phosphorescent bracelets are known. However, bracelets combining transparency with phosphorescence are not yet available on the market. Summary of the invention

[0003] The invention aims to overcome this deficiency by proposing a formulation that provides a phosphorescent effect visible at night for at least 10 minutes on a transparent or translucent bracelet, and generally on a watch component.

[0004] To this end, a new transparent or translucent phosphorescent material is proposed, with said material comprising by weight between 95 and 99.5% of a transparent thermoplastic or thermosetting resin, between 0.5 and 5% of phosphorescent compounds, between 0 and 0.3% of a porous silica, between 0 and 0.3% of at least one optical brightener, and between 0 and 5% of at least one colorant and / or at least one additive.

[0005] The watch component made with this material retains its transparency or translucency during the day with a sufficient luminescent effect at night.

[0006] Preferably, the material contains an optical brightener, useful for counteracting the yellowish tint of the phosphorescent pigment.

[0007] Preferably, the material also contains porous silica, which allows light to diffuse homogeneously throughout the watch component. Adding a limited percentage of porous silica to the material improves its luminescence properties. Brief description of the figure

[0008] Figure 1 illustrates a bracelet obtained with the formulation according to the invention. Detailed description of the invention

[0009] The invention relates to a phosphorescent and transparent or translucent material used for the mass production of a watch component. More specifically, it may be a casing component chosen from the non-exhaustive list including a case, a case back, a bezel, a bracelet link, a bracelet, a pin buckle, a clasp, a dial, a hand, and a dial marker. Even more specifically, it may be a bracelet 1 as shown in Figure 1 or a case. It may also be a movement component such as an oscillating weight.

[0010] The material comprises a thermoplastic or thermosetting resin transparent to the near-UV and visible spectra, i.e., in the wavelength range of 200 nm to 750 nm, with said resin forming the polymer matrix. It also comprises phosphorescent compounds. Preferably, it also comprises porous silica, which may also be described as nanoporous, and at least one optical brightener. Optionally, it may also comprise one or more colorants to obtain colored translucent versions of the material. Optionally, it may also comprise one or more additives.

[0011] The material comprises by weight (is made up by weight of) between 95 and 99.5% thermoplastic or thermosetting resin, between 0.5 and 5% phosphorescent compounds, between 0 and 0.3% porous silica, between 0 and 0.3% optical brighteners, and between 0 and 5% of all colorants and additives.

[0012] Preferably, the material comprises by weight (is made up by weight of) between 96.9 and 99.2% of the thermoplastic or thermosetting resin, between 0.7 and 3% of phosphorescent compounds, between 0.05 and 0.2% of porous silica, between 0.05 and 0.2% of optical brighteners, and between 0 and 3% of all colorants and additives.

[0013] More preferably, the material comprises by weight (is made up by weight of) between 97.84 and 98.94% of the thermoplastic or thermosetting resin, between 0.9 and 2% of phosphorescent compounds, between 0.08 and 0.15% of porous silica, between 0.08 and 0.15% of optical brighteners, and between 0 and 3% of all the colorants and additives.

[0014] More preferably, the material comprises by weight (is made up by weight of) between 98.54 and 98.94% of the thermoplastic or thermosetting resin, between 0.9 and 1.3% of phosphorescent compounds, between 0.08 and 0.13% of porous silica, between 0.08 and 0.13% of optical brighteners, and between 0 and 3% of all the colorants and additives.

[0015] If the material contains one or more colorants, they are preferably added to a masterbatch that is incorporated into the material during processing. For example, colorants may be added via a masterbatch that includes an additive such as wax. The masterbatch also contains a resin, which is preferably the same as that of the polymer matrix. In this case, the percentage of this resin will be included in the final product along with the percentage of resin in the polymer matrix. As a less preferred alternative that could alter the transparency of the material, the resin may be different from that of the polymer matrix. For example, it may be PEVA (Polyethylene Vinyl Acetate).

[0016] For transparent thermoplastic resin, this can involve thermoplastic elastomers and rigid thermoplastics. As an example For example, it may be one or more of the following polymers: acrylic copolymer thermoplastics, polyurethane thermoplastics (TPU), olefin thermoplastics (TPO), copolyesters (TPC), polyamides (TPA), polycarbonates (PC), polymethyl methacrylates (PMMA), polyethylene terephthalates (PET), polyethylene furanoates (PEF), styrene acrylonitrile (SAN), polysulfones (PSU), silicones, fluoroelastomers (FKM) and styrenic elastomeric thermoplastics (TPS).

[0017] For transparent thermosetting resin, i.e. crosslinked / vulcanized resins, examples may include silicones, fluorinated elastomers and polyurethane (PUR) elastomers.

[0018] The phosphorescent compound can be formed from a pigment or a pigment encapsulated in a shell. The pigment is preferably a rare-earth-doped alkaline-earth aluminate derivative. More specifically, the pigment can be Europium-, Dysprosium-doped strontium aluminate with the formula Sr(x)Al(y)O(z):Eu 2+ ,Dy 3+ In particular, it could be Sr4Ali4O25: Eu 2+ ,Dy 3+ or even from SrALCM: Eu 2+ ,Dy 3+ , possibly both present in the phosphorescent compound. Preferably, the pigments have a maximum diameter less than or equal to 20 pm measured by laser particle size analysis according to ISO 13320:2020, the restricted size of the pigments allowing to limit their impact on the transparency of the material and to avoid creating break initiation points in the material.

[0019] The pigments can optionally be encapsulated in an organic or mineral shell that is transparent to near-UV and visible light. The organic shell can typically be chosen from the polymers mentioned for the polymer matrix. For a mineral shell, it could, for example, be a silica (SiO2) shell obtained via a sol-gel process. Other examples of mineral shells include zirconium oxide (ZrC3), aluminum oxide (Al2O3), etc.

[0020] Preferably, the material contains porous silica. Advantageously, this is porous silica derived from diatom skeletons. For example, the Algica brand, produced by Swedish Algae Factory, is a suitable example. Typically, the average pore diameter is between 50 nm and 5 µm; the silica is therefore classified as nanoporous silica. Typically, the average pore diameter is around 500 nm, measured by laser particle size analysis according to ISO 13320:2020.

[0021] It could potentially be a synthetic nanoporous silica. For synthetic silica, the pores typically have an average diameter between 0.1 pm and 3 pm.

[0022] The material preferably also contains an optical brightener to give it a bright white appearance. The optical brighteners used are synthetic organic molecules derived from stilbenes, containing sulfonate groups that absorb light between 300 nm and 400 nm and re-emit in the blue-violet range. They are primarily used in the material as a whitening agent. Examples include distyryl biphenyl (DSBP) and diaminostilbene derivatives.

[0023] The material may also optionally include a system of at least one colorant and one or more additives. This system preferably comprises organic colorants that do not absorb within the emission wavelength ranges of the phosphorescent pigment. These may be fluorescent pigments or colorants that absorb primarily in the UV range and emit in the visible spectrum. For example, they may be organic fluorescent pigments or colorants such as those from the Radiant or Aralon® brands. Alternatively, they may be translucent pigments or colorants that absorb very little within the emission wavelengths of the phosphorescent pigment. For example, they may be translucent pigments or colorants from the Clariant brand. Other additives, such as metallic and pearlescent pigments and UV-blocking additives to protect the polymer matrix, may also be added.

[0024] The material can be molded using conventional methods. Thermoplastic materials are preferably injection molded. Materials requiring vulcanization are preferably compression or injection molded.

[0025] If desired, the polymerized material can then be decorated by digital printing or pad printing.

[0026] Tests were conducted with a thermoplastic polyurethane elastomer resin containing between 1% and 5% by weight of phosphorescent pigments (Europium and Dysprosium-doped strontium aluminate), 0.1% by weight of silica, and 0.1% by weight of optical brightener. The remaining 100% was the thermoplastic polyurethane elastomer resin. It was observed that with 1% phosphorescent pigments, the material was completely transparent, and with increasing pigment concentrations, it became translucent. An optimum was therefore achieved with a phosphorescent pigment content close to 1% by weight. Luminance analysis according to ISO 17514:2024 showed that daytime transparency was maintained with sufficient luminescence at night. At time 0, the luminous intensity was 8.7 mCd / m². 2 and after 600 seconds, it is 1.6 mCd / m 2 .

Claims

DEMANDS 1. Transparent or translucent single-layer watch component made of a phosphorescent material, said phosphorescent material comprising by weight between 95 and 99.5% of a transparent thermoplastic or thermosetting resin, between 0.5 and 5% of phosphorescent compounds, between 0 and 0.3% of a porous silica, between 0 and 0.3% of at least one optical brightener, and between 0 and 5% of at least one colorant and / or at least one additive, said phosphorescent compounds having a maximum diameter less than or equal to 20 pm.

2. Watch component according to the preceding claim, characterized in that said material comprises by weight between 96.9 and 99.2% of the thermoplastic or thermosetting resin, between 0.7 and 3% of phosphorescent compounds, between 0.05 and 0.2% of porous silica, between 0.05 and 0.2% of the optical brightener, and between 0 and 3% of the colorant and / or additive.

3. Watch component according to any one of the preceding claims, characterized in that said material comprises by weight between 97.84 and 98.94% of the thermoplastic or thermosetting resin, between 0.9 and 2% of phosphorescent compounds, between 0.08 and 0.15% of porous silica, between 0.08 and 0.15% of the optical brightener, and between 0 and 3% of the colorant and / or additive.

4. Watch component according to any one of the preceding claims, characterized in that said material comprises by weight between 98.54 and 98.94% of the thermoplastic or thermosetting resin, between 0.9 and 1.3% of phosphorescent compounds, between 0.08 and 0.13% of porous silica, between 0.08 and 0.13% of the optical brightener, and between 0 and 3% of the colorant and / or additive.

5. Watch component according to any one of the preceding claims, characterized in that the transparent thermoplastic resin is selected from polyamide, polycarbonate, polymethyl methacrylate, the polyethylene terephthalate, polyethylene furanoate, styrene acrylonitrile, polysulfone, polyurethane, olefins, styrene, copolyester, elastomer and fluoroelastomer.

6. Watch component according to any one of claims 1 to 5, characterized in that the transparent thermosetting resin is selected from silicones, fluorinated elastomers and polyurethane elastomers.

7. Watch component according to any one of the preceding claims, characterized in that the porous silica is derived from diatom skeletons.

8. Watch component according to any one of the preceding claims, characterized in that the nanoporous silica has an average pore diameter between 50 nm and 5 pm.

9. Watch component according to any one of the preceding claims, characterized in that the phosphorescent compounds comprise a phosphorescent pigment which is a rare-earth-doped alkaline-earth aluminate derivative.

10. Watch component according to the preceding claim, characterized in that the phosphorescent pigment is an alkaline earth aluminate derivative doped with Europium, Dysprosium of formula Sr(x)Al(y)O(z): Eu 2+ ,Dy 3+ .

11. Watch component according to the preceding claim, characterized in that the phosphorescent pigment is SRAI14O25: Eu 2+ ,Dy 3+ and / or SrAI2O4: Eu 2+ ,Dy 3 .

12. Watch component according to any one of claims 9 to 11, characterized in that the phosphorescent pigment has a maximum diameter less than or equal to 20 pm measured by laser particle size analysis according to ISO 13320:2020.

13. Watch component according to any one of the preceding claims, characterized in that the optical brightener is a stilbene derivative containing a sulfonate group.

14. Watch component according to any one of the preceding claims, characterized in that it is a case, a case back, a bezel, a bracelet link, a bracelet (1), a pin buckle, a clasp, a dial, a hand, a dial marker or an oscillating weight.

15. Watch component according to one of the preceding claims, characterized in that it is a bracelet (1) or a case.

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