Method for manufacturing enamel processed timepiece component

Abstract

To provide a method for manufacturing a timepiece component including colored enamel plating.SOLUTION: A method includes: a step of providing a base material 20 selected from materials withstanding an enamel baking temperature; a step 22 of formulating a colored enamel composition constituting colored enamel plating of a timepiece component, including a step 24 of sealing a color pigment in a transparent protective shell made of an inorganic material, and a step 25 of mixing the sealed coloring pigment with an enamel formulation; a step 27 of applying at least one layer of the formulated colored enamel composition onto a reception region on the base material; and a step 28 of baking the layer of the colored enamel composition included in the reception region.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a watch component including an enamel plating mixed with color pigments.

[0002] The invention also relates to a timepiece featuring such an enamel plating and to a timepiece, such as a wristwatch, incorporating such a timepiece. [Background technology]

[0003] In the field of watchmaking technology, watch components comprising enamel plating, such as enamel dials, have been known for a very long time. Such enamel dials have the interesting feature that they are practically unalterable and can be used to create decorations in a very bright and rich color palette, including color pigments containing cadmium or selenium.

[0004] However, such colour pigments no longer meet the certification standards for watch exterior parts due to their toxicity.

[0005] It is therefore clear that there is a need to find an alternative solution to the prior art. Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has a particular aim to remedy various drawbacks of the prior art.

[0007] The present invention further aims to obtain a watch component comprising an enamel plating containing non-toxic color pigments, in particular bright color pigments. [Means for solving the problem]

[0008] To this end, one aspect of the invention relates to a method for producing a watch part including a colored enamel plating, the method comprising the steps of: Providing a substrate selected from among materials capable of withstanding enamel firing temperatures; - preparing a colored enamel composition constituting the colored enamel plating of said watch part, said step including encapsulating colored pigments in a transparent protective shell made of inorganic material and mixing said encapsulated colored pigments with an enamel formulation; applying at least one layer of the formulated colored enamel composition to a receiving area on a substrate; - firing the layer of colored enamel composition contained in the receiving area; Includes.

[0009] In another embodiment, In the encapsulation step, a process that creates a homogenous layer of conformal material made of metal oxide is applied to the entire surface of each color pigment. The deposition process is carried out using ALD and / or microemulsion techniques. The colored enamel composition contains up to 30% by weight of encapsulated color pigments. The colored enamel composition contains up to 50% by weight of encapsulated color pigments. A treatment step for the receiving area on the substrate onto which the layer of colored enamel composition is to be applied, said step comprising the application of a degreaser and / or adhesive to said receiving area. A finishing / finishing step on the substrate in the areas that will receive the layer of colored enamel composition, said step including a cutting sub-step and a polishing sub-step. Each pigment is a brightly colored pigment. Each color pigment is an inorganic pigment or a non-toxic inorganic pigment.

[0010] Another aspect of the invention relates to a watch component that can be obtained using this method.

[0011] Advantageously, the watch component comprises a substrate selected from among materials configured to withstand enamel firing temperatures, and a receiving area on the substrate comprises a colored enamel plating including encapsulated light-colored inorganic non-toxic pigments.

[0012] Advantageously, the timepiece part also includes a plating forming a decorative element.

[0013] Another aspect of the invention also relates to a timepiece including such a timepiece part. [Brief description of the drawings]

[0014] Other characteristics and advantages of the present invention will appear more clearly on reading the following description of particular embodiments of the invention, given purely as illustrative and non-limiting examples, and from the accompanying drawings, in which: [Figure 1] 1 is a schematic diagram of a watch including a watch component, such as a dial, that is plated with colored enamel, according to one embodiment of the present invention. [Diagram 2] 1 shows a flow chart for a method for manufacturing a watch component, such as a dial, including a brightly pigmented enamel plating, according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] With reference to figures 1 and 2, the invention relates to a method for producing a watch part 2 comprising a coloured enamel plating. Such a method is used to obtain a watch part 2 for a watch 1, comprising a substrate provided with a receiving area 8 comprising this enamel plating mixed with brightly coloured pigments. This receiving area 8 comprised on the outer surface of the substrate / watch part 2 can comprise all faces of the substrate / watch part 2, or only one face, or one or more separate parts of a single face or of several different faces. In these different variants, this plating 10 can therefore participate in forming a decorative element on this watch part 2.

[0016] 1, in order to better understand the invention, the watch part 2 is in this case an exterior part such as a dial 2 of a watch 1. This dial 2 comprises, on its visible face 9, a coloured enamel plating 10 located in its receiving area 8. However, it should be noted that this watch part 2 could be other exterior parts such as a bezel, a moon phase, a date disc 7, dial indexes, etc.

[0017] In this embodiment, the timepiece, which may be a wristwatch, comprises an analog display dial 2 and hour, minute and second hands 3a, 3b and 3c which can move towards hour markers 5 marked on an hour display circle 4. In the illustrated example, the dial 2 includes an opening 6 passing through the entire thickness of the dial 2, under which a date disc 7 moves.

[0018] In this respect, such a manufacturing method comprises a providing step 20, in which a substrate is provided for forming said watch part 2. Such a step 20 may comprise a stamping sub-step 21, in which the substrate is stamped into a plate with the dimensions of the watch part 2 to be produced, said plate having a thickness suitable for said part 2. This plate, and therefore this substrate, is made of a material adapted to withstand enamel firing temperatures. These temperatures are preferably above 500 degrees Celsius, or between 700 and 1,300 degrees Celsius. By way of example, this material may be a metal or metal alloy, for example steel, or a ceramic.

[0019] Such materials may be transparent, such as quartz, spinel or corundum, especially single or polycrystalline materials such as sapphire. Amorphous materials such as mineral glasses may also be used, provided their softening point is higher than the enamel firing temperature.

[0020] The method then comprises a preparation step 22 of a coloured enamel composition. This step 22 then comprises a production sub-step 23 of an enamel formulation. In particular, this may be a production sub-step 23 of a colourless, coloured, semi-transparent or transparent enamel formulation. This production sub-step 23 is carried out using operating and manufacturing methods that are not described in detail here but are well known in the prior art and make it possible to obtain a colourless, coloured, semi-transparent or transparent enamel formulation. It should be noted in particular that this formulation is produced using an aqueous or oily base that is mixed with the enamel. Furthermore, the colourless or coloured enamel formulation is also called the "initial colourless or coloured enamel composition".

[0021] This step 22 then comprises an encapsulation sub-step 24, in which the coloured pigments are encapsulated in a protective transparent shell of inorganic material, also known as a "protective transparent envelope of inorganic material". Such sub-step 24 comprises encapsulating each pigment used in the coloured enamel composition in such a transparent protective shell, in order to improve in particular the thermal and / or chemical stability characteristics of said pigment. In fact, this improved thermal stability allows each encapsulated pigment to maintain its complete crystalline structure even when the temperature of the medium in which it is present is raised up to the enamel firing temperature.

[0022] Such pigments are preferably bright or vivid colors, such as red, yellow, orange, green, pink, or blue, and variations thereof. "Bright colors" refer to strong colors in the CIELAB color space, with an optical shape measured in standard illuminant D65 transmission mode at an observer angle of 10° and d:0° with an L* component greater than 40 (in accordance with CIE No. 15, ISO 7724 / 1, DIN 5033 Teil 7, ASTM E-1164). It should be noted that CIELAB is the 1976 CIEL*a*b* color space, which is used to characterize surface colors, among others.

[0023] In this embodiment of the invention, these color pigments are inorganic pigments. In particular, these pigments are non-toxic inorganic pigments. Such pigments may belong, non-exhaustively and without limitation, to the (oxy)nitride family, the cerium sulfide family, or the phosphate family. It should be noted that pigments from the (oxy)nitride family are usually bright in color ranging from red to green and blue to yellow. For pigments belonging to the cerium sulfide family, they are basically bright in color ranging from red to orange. And for pigments from the phosphate family, they have bright blue, green or purple colors.

[0024] This encapsulation substep 24 comprises a process of forming / applying a homogeneous matching material layer made of metal oxide over the entire surface of each pigment. To that end, this material is deposited on the surface at least once to form such a layer. In this respect, the layer forms a protective shell encapsulating each pigment. It is understood that the cycles of depositing this material on this surface can be set to obtain a predetermined thickness of this layer. In practice, the thickness of the layer can vary depending on the characteristics of the colorless enamel formulation to be applied to the watch part 2 and / or depending on the characteristics of the colored enamel plating.

[0025] It is understood, of course, that such layers are transparent so as not to alter the true color of the light colored pigments.

[0026] The metal oxide that makes up the homogeneous conformal material layer can be, but is not limited to and non-exhaustive, silicon dioxide of the chemical formula SiO2, aluminum oxide of the chemical formula Al2O3, zinc oxide of the chemical formula ZnO, or titanium oxide of the chemical formula TiO2.

[0027] In this encapsulation substep 24, the formation of the layer and thus of this protective shell encapsulating each pigment can be carried out, for example, using a technique for depositing at least one atomic layer, well known under the acronym ALD for "atomic layer deposition". In the context of the present invention, this technique therefore makes it possible to deposit a thin layer on the surface of each colour pigment by chain reaction in the gas phase with a metal oxide precursor, such as trimethylaluminum, in the case where the metal oxide is aluminium oxide.

[0028] In one embodiment, the layer encapsulating each pigment can be formed using a microemulsion technique that allows the deposition of a metal oxide on the surface of the pigment by microemulsion reaction with a precursor of this metal oxide, which in the context of the present invention can be tetraethyl orthosilicate when the metal oxide is silicon dioxide.

[0029] In another variation, the layer encapsulating each pigment can be formed using a combination of these two techniques, for example, but not limited to, starting with the use of the ALD technique and continuing with the microemulsion technique.

[0030] It will be appreciated that such sub-step 24 is used to encapsulate each pigment within a protective shell formed by a transparent layer of material contained on the surface of the pigment. Such a layer may include: its homogeneity, its suitability, a thickness of 2 nm to 1,000 nm, preferably 10 nm, preferably 30 nm or preferably 50 nm, its stiffness, and / or -Its transparency It is characterized by:

[0031] This layer, and therefore the shell, is at the same time Oxidation at enamel firing temperatures, Acidic media, especially weakly acidic with a pH of ≒ 4.5 Exposure to ultraviolet light, Cosmetics It should also be noted that it provides effective protection of the color pigments against

[0032] The preparation step 22 of the colored enamel composition also includes a mixing sub-step 25, in which the encapsulated colored pigment is mixed with a colorless enamel formulation. This mixing sub-step 25 is used to obtain a colored enamel composition in which the encapsulated colored pigment is dispersed. In this sub-step 25, the resulting mixture, which corresponds to the colored enamel composition, contains a mass percentage of the encapsulated colored pigment of at most 30% or at most 50%.

[0033] This weight percentage is preferably between 2% and 30%.

[0034] Such weight percentage is preferably between 5% and 30%.

[0035] Such weight percentage is preferably between 5% and 10%.

[0036] It is understood that these weight percentages of color pigments serve to achieve a compromise between color, transparency and color strength in the mixture while ensuring good final properties (e.g., mechanical properties, homogeneity, etc.).

[0037] It should also be noted that this mixing can be done by wet mixing or any other mixing method known to one of ordinary skill in the art.

[0038] The method then comprises a treatment step 26 of said receiving area 8 of the substrate on which the coloured enamel plating is to be applied. In such a step 26, a degreaser and / or adhesive can be applied to this receiving area 8 intended to contain this plating 10.

[0039] The method then comprises an application step 27, in which at least one layer of the coloured enamel composition thus prepared is applied to a receiving area 8 of the substrate. It is understood that the receiving area 8 can be, for example, all or part of the visible surface 9 of the watch part 2 when this watch part 2 is mounted on the watch 1. In this step 27, a layer of the coloured enamel composition can be deposited on this receiving area 8 by grinding, spraying and / or printing.

[0040] The method then includes a firing step 28, in which at least said layer of colored enamel composition contained in the receiving area 8 of the substrate is fired. In this step, the substrate is fired at a temperature of 300° C. to 1,200° C., preferably 500° C. to 800° C., preferably 690° C., with a residence time of 1 minute to 10 minutes, preferably 5 minutes. This firing step 28 is carried out in air or in a controlled atmosphere, for example argon, nitrogen or under vacuum.

[0041] It should be noted that this step 28 may include a drying sub-step 29, in which the layer of colored enamel composition covering the receiving area 8 of the substrate is dried before firing. Such a sub-step 29 is used to remove any moisture present in the layer before firing. All of the usual drying methods can be used, such as air drying, oven drying or radiation drying.

[0042] It should be noted that the sequence of application steps 27 and firing steps 28 in the method can be repeated as necessary in order to obtain a specific or desired thickness of colored enamel plating on the image receiving area 8 and on the watch part 2. In this respect, the thickness depends on the number of layers that make up the colored enamel plating 8. It is understood that this thickness depends in particular on the properties of the colored enamel plating obtained on the watch part 2, in particular its aesthetic properties.

[0043] The method also comprises a finishing / finishing step 30 on the substrate, in which a layer of fired colored enamel composition is applied to the image-receiving area, in order to obtain this watch part 2 comprising the colored enamel plating 10. This step 30 can therefore comprise a stone-cutting sub-step 31 on this substrate, in particular on the layer of fired colored enamel composition. This sub-step 31 can be carried out until the desired uniform thickness of the colored enamel plating 10 is obtained. This step 30 can also subsequently comprise a polishing or texturing sub-step 32, in which this substrate, in particular on the layer of fired colored enamel composition that has lost its luster during the stone-cutting sub-step 31, is polished or textured.

[0044] This step 30 may also include a machining sub-step 33 to cut the substrate for attachment to the watch 1, if necessary.

[0045] It should be noted that if the watch part is a dial 2, machining operations can be performed on the dial 2 to form through openings into which the drive shafts of the hands 3a to 3c can be inserted. In this respect, appliqué / indexing operations can also be performed if they have not already been performed. These appliqués can be drawn, stamped or glued directly onto the visible surface, or they can be glued by parts that penetrate the dial 2 using the holes formed during the machining operations.

[0046] The above description is of preferred embodiments and should not be construed as limiting in any way, particularly with respect to the types of color pigments used to color the enamel. Indeed, color pigments other than light color pigments are also part of the present invention. [Explanation of symbols]

[0047] 1. Watch 2. Dials and other watch parts 3a hour hand 3b minute hand 3c second hand 4 Time Markers 5 Time display circle 6 Openings 7 Date Disc 8 Receptacle area for substrates and watch components 9 Visible surfaces of watch parts 10 Colored enamel coating

Claims

1. A method for manufacturing a watch part (2) including a colored enamel plating (10), comprising the steps of: - providing a substrate (20) selected from among materials capable of withstanding enamel firing temperatures; a step (22) of preparing a colored enamel composition constituting the colored enamel plating of said watch part (2), comprising the encapsulation (24) of colored pigments in a transparent protective shell made of inorganic material and the mixing (25) of said encapsulated colored pigments with the enamel formulation; - applying (27) at least one layer of the formulated colored enamel composition to a receiving area (8) on the substrate; - firing (28) the layer of colored enamel composition contained in the receiving area (8); The method includes:

2. The method of claim 1 , wherein in the encapsulating step, a process for forming a homogeneous conformal material layer made of metal oxide is applied to the entire surface of each color pigment.

3. 2. The method according to claim 1, wherein a process for forming a homogeneous conformal material layer made of metal oxide is applied to the entire surface of each color pigment, said process being carried out by using ALD technology and / or microemulsion technology.

4. The method of claim 1 , wherein the colored enamel composition comprises up to 30% by weight of encapsulated color pigments.

5. The method of claim 1 , wherein the colored enamel composition comprises up to 50% by weight of encapsulated color pigments.

6. 2. The method of claim 1, further comprising a treatment step (26) of the receiving area on the substrate onto which the layer of colored enamel composition is to be applied, said step (26) comprising the application of a degreaser and / or adhesive to the receiving area.

7. 2. The method according to claim 1, further comprising a finishing / finishing (30) step on the substrate carried out on the area (8) that will receive the layer of colored enamel composition, said step (30) comprising a stone-cutting sub-step (31) and a polishing sub-step (32).

8. The method of claim 1 , wherein each pigment is a light colored pigment.

9. The method of claim 1 , wherein each color pigment is an inorganic pigment or a non-toxic inorganic pigment.

10. A watch part (2) obtainable using the method according to any one of the claims 1 to 9.

11. 11. The watch component (2) according to claim 10, comprising a substrate selected from among materials configured to withstand enamel firing temperatures, the receiving area (8) on said substrate comprising a colored enamel plating including encapsulated light-colored inorganic non-toxic pigments.

12. 11. A watch part (2) according to claim 10, comprising a substrate selected from among materials adapted to withstand enamel firing temperatures, a receiving area (8) on said substrate comprising a coloured enamel plating comprising encapsulated light-coloured inorganic non-toxic pigments, said plating (8) forming a decorative element.

13. A watch (1) comprising a watch part (2) according to claim 10.

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