EP3723539A1

EP3723539A1 - Material for timepieces and jewellery

Info

Publication number: EP3723539A1
Application number: EP18807388.6A
Authority: EP
Inventors: Nicolas François; Stéphane Lauper; Gregory Kissling; Stewes Bourban; Agnès Marlot Doerr
Original assignee: Swatch Group Research and Development SA
Current assignee: Swatch Group Research and Development SA
Priority date: 2017-12-14
Filing date: 2018-11-29
Publication date: 2020-10-21
Also published as: JP2021504014A; CN111465332A; JP2022169582A; US11583045B2; US20200383438A1; WO2019115249A1; JP2024105470A

Abstract

The present invention relates to a part, particularly for timepieces or jewellery, made of a material comprising a synthetic matrix (2) filled with particles (3) made of a precious or semi-precious stone, said particles (3) having a particle size d90 between 50 μm and 20 mm, preferably between 100 μm and 1 mm, and, more preferably between 150 μm and 500 μm, said particles being coated with a coupling agent having the function of strengthening the connection between said particles and the synthetic material.

Description

MATERIAL FOR PIECE OF WATCHMAKING AND JEWELERY

Object of the invention

The present invention relates to a part made of a material having a particular aesthetic effect through the dispersion of powders of semi-precious or precious stones such as diamond within a synthetic matrix. It relates more particularly to a timepiece or jewelery made in whole or part of this material.

Technological background

Diamond is a commonly used material, whether for its properties or its aesthetic appearance. In the dispersed state, it is rather used to confer particular properties on a matrix. There are thus many works dealing with nano-diamonds distributed within a matrix to improve the thermal conductivity or even the resistance to wear. By cons, to give an aesthetic appearance to a room, the diamond is used cut and crimped within the room. To the applicant's knowledge, the use of diamond powders dispersed within a matrix to improve the aesthetic appearance of the material has not been explored. It is the same for other semi-precious or precious stones such as ruby, etc. Summary of the invention

The main object of the present invention is to propose a new material which is aesthetically attractive for the production of timepieces and jewelery. For this purpose, the present invention provides a material comprising a matrix made of a synthetic material filled with a micron-sized precious or semi-precious stone powder which gives the material its particular aesthetic appearance while conferring on it an increased resistance (hardness and Young's modulus).

Advantageously, the particles, for example diamond particles, have a diameter d90 of between 50 μm and 2 mm, and preferably between 100 μm and 1 mm and more preferably between 150 μm and 500 μm. said particles being covered with a coupling agent having the function of reinforcing and stabilizing the bond between said particles and the synthetic material.

Due to the presence of coupling agent around the particles, the part is reinforced and is more stable in time and the dispersion of the particles in the synthetic material is better controlled during manufacture.

The coupling agents must have reactive functions to chemically bond to the particles on the one hand and the organic functions of the synthetic material and preferably the coupling agent is a compound selected from the family of organosilanes, titanates or zirconates.and the coupling agent is between 0.1 and 5% by weight of the mixture of synthetic material and particles. Advantageously, the coupling agent is chosen from 3-glycidyloxy epoxy propyltrimethoxysilane, pyrophosphatotitanate or isopropyltri [di (octyl) phosphato] titanate or zirconium tetra-n-propanolate.

Advantageously, especially for a diamond powder, the d90 is greater than or equal to 150 μm to enhance the sparkling effect of the diamond. Depending on the hardness of the matrix, the field of application is different. Thus a flexible matrix is preferred for the manufacture of bracelets while a hard matrix is preferred for the manufacture of dressing parts or movement. Depending on the type of stone, the size of the powder and its percentage within the matrix, the visual can be modulated. Thus, a wide range of colors, a greater or lesser visibility of the particles constituting the powder, a more or less marked sparkling effect or depth effects as a function of the transparency level of the matrix can be obtained.

This new material also makes it possible to value production waste from the size of diamonds or other precious or semi-precious stones used especially in the field of watchmaking.

Other advantages will emerge from the features expressed in the claims, the detailed description of the invention illustrated below with the aid of the accompanying drawing given by way of non-limiting example.

Brief description of the figures

FIG. 1 represents a schematic view of a watch provided with a bracelet made with the material according to the invention. Detailed description of the invention

The present invention relates to a part and, in particular to a timepiece or jewelery, made of a composite material. By the piece is meant both small elements intended to be affixed to a substrate such as a decorative element (logos, etc.) that a massive structural part.

The material, illustrated in FIG. 1 for application in a bracelet 1, comprises a synthetic matrix 2 loaded with a powder 3 a precious stone such as diamond, ruby, sapphire and emerald or a fine stone, also called semi-precious stone, such as quartz, topaz, garnet, or even organic stone as mother-of-pearl and amber to name a few. Precious or semi-precious stone is understood to mean both a natural stone and a synthetic stone. By way of illustration, the examples will relate more specifically to a diamond powder.

According to the invention, the powders are micrometric. The particle size of the powder is measured by laser diffraction according to ISO 13320: 2009 and expressed hereinafter by the diameters d10 and d90 for which respectively 10 and 90% (in number) of the particles have a diameter less than or equal to given diameter (cumulative distribution). Preferably, the powders have a particle size d90 of between 50 μm and 2 mm, more preferably between 100 μm and 1 mm and even more preferably between 150 μm and 500 μm. Below a particle size distribution with a dome of 150 μm, the particles no longer have a sparkling appearance and are less identifiable as valuable particles. However, with the finer particle sizes, it is possible to disperse a larger amount of diamonds in the resin and thus to obtain a material with a larger carat. These powders preferably have a fine particle size distribution (better dispersibility) of between 1 .mu.m and 100 .mu.m, more preferably between 20 .mu.m and 50 .mu.m and even more preferably between 1 and 20 .mu.m with a cumulative distribution d.sub.90 of between 5-15.degree. pm and d10 between 3 and 5 pm. The diamonds can be of natural origin, which brings a fluorescence of certain particles under ultraviolet radiation at 365 nm. The natural origin gives a creamy shine to the powder. The diamonds can also be synthetic or monocrystalline which gives a glossy golden powder or polycrystalline powder in which case the powder is glossy black. Preferably, the matrix is made from a transparent base resin to be able to visualize the particles within the matrix. Depending on the percentage of particles, the latter is likely to become opaque. Nevertheless, the particles close to the surface of the material will always be able to offer a certain brightness, as long as the size of this one is sufficient

Depending on the part to be produced, the matrix may be flexible or rigid.

A flexible matrix, i.e. having a Shore A hardness (ISO 7619-1: 2010) of less than or equal to 80, is chosen for the manufacture of flexible components such as a bracelet or the decoration of components by overmoulding for a "soft touch" appearance, such as a telescope or a crown. The matrix is a transparent elastomeric matrix providing the elastic properties required for the application. Preferably, the choice of the elastomer is a fluorinated elastomer (FKM, FFKM) transparent known for its high resistance to aging. The choice can however be made on other transparent elastomers such as hot vulcanizable silicone (EVC), polyurethane elastomers (PUR) or thermoplastic elastomers (TPE). The percentage of powder is adjusted to maintain the flexibility of the material. It is thus between 0.5 and 40%, preferably between 0.5 and 30% and, more preferably, between 1 and 5% by weight relative to the total weight of the material. A charge rate of less than or equal to 5% makes it possible to preserve the transparency of the material without drastically modifying its mechanical properties. The transparency of the composite material being preserved, it is possible to achieve optical effects such as depth effects with the material underneath when the composite material is used as a decorative element. Moreover, the maintenance of the properties of the base material makes it possible to ensure a good use for the molding bracelets or the decoration of timepieces by overmolding.

Tests have been successfully performed on a Solvay FFKM base resin (grade 5910M). The diamond powder with a d90 of 50 μm was dispersed by mixing on an open mixer (calendering) in the elastomer. 2.5% by weight of natural or synthetic powders of monocrystalline and polycrystalline diamines could be dispersed without modifying the characteristics of the elastomer and its viscosity with, ultimately, on the product obtained the desired sparkling effect. Additional tests were performed with RTV silicone

(Room temperature vulcanization) loaded with 30% by weight for powders of natural or synthetic diamonds mono and polycrystalline with a d90 of 60 pm. No cracking was observed on the elastomer. In the end, the product is opaque due to the high percentage of diamond powders. It nevertheless presents an attractive rendering. The addition of 30% by weight of diamond powder has led to an increase of 10 points of the material A shore with nevertheless a value always below the value of 75 points, typically between 60 and 70 points A shore desired for the comfort of the bracelet. It will be pointed out that such a high percentage tends to damage the mixer rollers because of the hardness of the diamond, which industrially is undesirable. In this case, it is preferable to disperse the micro-diamonds beforehand in a liquid solution of the hot-vulcanizable elastomer. FKM granules loaded with micro-diamonds are then evaporated off from the solvent.

The flexible matrix as described above can be replaced by a rigid / hard matrix for the production of trim such as a middle part, a bottom, a bezel, a pusher, a bracelet link, a dial, a needle , a dial index, etc. or even moving parts such as a bridge or a plate. We "Hard matrix" means a matrix having a Shore D hardness greater than or equal to 80 (ISO 868: 2003).

In the case of a rigid matrix, the increase in hardness following the addition of diamonds is less critical than for a flexible matrix. Therefore, the percentage of powder can be significantly higher with percentages that can rise above 50% by weight. Thus, the percentage by weight is between 0.5 and 90%, preferably between 5 and 80%, and more preferably between 30 and 70%. The choice of the percentage is made according to the level of transparency, the desired viscosity of the resin and the desired final rendering. The matrix is a transparent resin which may, by way of example, be a thermosetting resin chosen from the family of acrylics, polyurethanes, epoxides or a copolymer resin combining monomers of the aforementioned families. The choice of the resin can also be carried on an acrylic thermoplastic resin such as PMMA or be carried a thermoplastic polycarbonate resin (PC). According to the invention, the diamond powder is pre-dispersed in the resin before adding the hardener. The hardener is added before pouring the resin into the mold. It is thus possible to make inserts such as logos and decorations of all kinds, which are subsequently assembled on the trim parts for example by overmolding, gluing, welding, riveting or screwing. It is also possible to directly mold the timepieces whose mechanical characteristics will depend mainly on the selected resin and the diamond charge rate. It is also conceivable to inject the filled resin by syringe deposition within a housing machined for example in a pusher, in a bezel or in a sapphire crystal. After removal within the housing, the resin is fired and the excess resin is removed by polishing. This incrustation within a part is facilitated by the good fluidity of the resin (<1000 mPa.s ¹ ), e.g. epoxy, the cooking can be performed at a low temperature of 80 ° C, typically. Tests were carried out with a transparent thermosetting resin (refractive index of 1.5) two epoxy-amine components with a Shore 90D hardness. 60% by weight of micro-diamonds were dispersed in the epoxy resin with an epoxy silane (3-glycidyloxy-propyltrimethoxysilane epoxy) GLYEO of the mark Dynasylan ^® as a coupling agent between the micro-diamonds and the epoxy resin. The tests were carried out with natural and synthetic micro-diamonds mono and polycrystalline with for each type of diamond a d90 of 100 and 500 pm tested. For natural diamonds, the product has a cream aspect more or less brilliant depending on the size of the particles. For monocrystalline synthetic diamonds, the product has a golden appearance also more or less brilliant depending on the size of the particles. For polycrystalline synthetic diamonds, the product has a black appearance. Additional tests were also carried out with scrap of clockwork ruby stones of formula A OsCr crushed to obtain a d90 of 500 μm and dispersed in a transparent epoxy resin with a percentage of 60% by weight. A beautiful color effect was observed with visible ruby particles in the matrix.

In summary, we see that a wide range of effects (colors, brightness, transparency, visibility of the particles of the powder) can be obtained depending on the type of stone, its size and its percentage within the matrix. Finally, we will specify that dyestuffs, fluorescents and / or phosphorescent can be added to the matrix (flexible or rigid) to adapt the aesthetics of the room as needed.

It will also be noted that, in one variant, the matrix may be opaque and in this case stone particles having a size of between 100 and 500 μm will be preferred. Naturally the part obtained by injection, molding or other will be polished to reveal the stone particles on the surface.

Claims

1. Part, in particular of jewelery or timepieces, made of a material comprising a matrix (2) of synthetic material filled with particles (3) of a precious or semi-precious stone, said particles (3) having a particle size distribution d90 between 50 pm and 2 mm, preferably between 100 pm and 1 mm, and more preferably between 150 pm and 500 pm, said particles being covered with a coupling agent whose function is to reinforce the bond between said particles and the synthetic material.

2. Part according to claim 1, characterized in that the coupling agent is a compound selected from the family of organosilanes, titanates or zirconates.

3. Part according to claim 1 or 2, characterized in that the coupling agent represents between 0.1 and 5% by weight of the mixture of synthetic material and particles.

4. Part according to one of claims 1 to 3, characterized in that the coupling agent is chosen from 3-glycidyloxy epoxy propyltrimethoxysilane, pyrophosphatotitanate isopropyltri [di (octyl) phosphato] titanate or zirconium tetra- n-propanolate.

5. Part according to any one of the preceding claims, characterized in that the particle size is between 1 pm and 100 pm, preferably between 1 and 50 pm, and more preferably between 1 and 20 pm with a d90 between 8. and 15 pm and a d10 between 3 and 5 pm to maximize the rate of gemstone charge in the matrix

6. Part according to any one of the preceding claims, characterized in that the matrix (2) is a flexible matrix, said material comprising the flexible matrix having a Shore A hardness less than or equal to 80, and preferably between 50 and 75.

7. Part according to claim 6, characterized in that the matrix (2) of synthetic material is made of a transparent elastomeric resin selected from the list comprising fluorinated elastomers, hot-vulcanizable silicone, polyurethane elastomers and thermoplastic elastomers.

8. Part according to claim 6 or 7, characterized in that the percentage of particles (3) is between 0.5 and 40%, preferably between 0.5 and 30%, and more preferably between 1 and 5% by weight.

9. Part according to any one of claims 1 to 5, characterized in that the matrix (2) is a rigid matrix, the material comprising the matrix (2) having a shore hardness D greater than or equal to 80.

10. Part according to claim 9, characterized in that the percentage of particles (3) is between 0.5 and 90%, preferably between 5 and 80%, and more preferably between 30 and 70% by weight.

11. Part according to claim 9 or 10, characterized in that the matrix (2) of synthetic material is made of a transparent acrylic thermoplastic resin or polycarbonate, or in a transparent thermosetting resin selected from the list comprising the family of acrylics, polyurethanes, epoxies and copolymers combining monomers of the aforementioned families.

12. Part according to any one of the preceding claims, characterized in that the particles (3) are diamond particles, emerald, sapphire or rubies of natural or synthetic origin.

13. Part according to claim 12, characterized in that the diamond is of natural origin to give a cream color to the material, or of synthetic and monocrystalline origin to impart a golden color to the material or of synthetic and polycrystalline origin to confer a black color to the material.

14. Part according to any one of the preceding claims, characterized in that the matrix (2) also comprises dyestuffs, fluorescent and / or phosphorescent.

15. Part according to any one of the preceding claims, characterized in that in watchmaking, it forms a part of the movement or a piece of clothing.

16. Part according to claim 15, characterized in that the part of the movement or the dressing part comprises in volume said material.

17. Part according to claim 15, characterized in that the part of the movement or the dressing part comprises a portion made of said material, said part being assembled on the surface of the part or being housed within a recess in the room.

18. Part according to claim 17, characterized in that the part is a logo, a decor or an element conferring a soft touch to the room.

19. Part according to any one of claims 15 to 18, characterized in that, for a material comprising a rigid matrix, it is a piece selected from the list comprising a bracelet link, a clasp, a middle part , a pusher, a crown, a bezel, an ice, a dial, a needle, a dial index, a bottom, a plate, a wheel and a bridge.

20. Part according to any one of claims 15 to 18, characterized in that, for a material comprising a flexible matrix, it is a bracelet (1).

21. Watch comprising the part according to any one of claims 15 to 20.