Method for obtaining article having shining polycrystalline surface

Abstract

The invention relates to a method for obtaining a decorative article (5) having a shiny appearance, comprising the following steps:-providing or preparing a model (1) having a surface (1a) of a polycrystalline structure to be replicated,-preparing a replicating die (2) of said surface (1a) using a polymeric material, -subsequently optionally performing the following steps:-producing a solid body (4) on the replication surface (2a) of at least one part of the replication female mold (2); the method is characterized in that during the above-mentioned steps, one or more operations are performed to impart a specific optical effect and / or functional appearance to the decorative article (5), said one or more operations being selected from the group consisting of:-locally modifying the polycrystalline structure of the model (1) prior to the preparation of the replication female mold (2),-modifying the shape of the replication female mold (2),-modifying the polycrystalline structure of the model (1) prior to the preparation of the replication female mold (2), -selectively producing a solid body (4) on certain portions of the replication surface (2a) of the replication die (2); the decorative article (5) is a replication female mold (2), or if optional steps are performed, the decorative article is an entity (4). The invention also relates to a decorative article (5) produced according to the above method.

Description

Technical Field

[0001] The present invention relates to a method for producing an item having a shiny effect, preferably the appearance of a precious material, on at least one of its surfaces. In particular, the item is an external timepiece part, such as a dial. Background Art

[0002] Methods for producing objects with decorative surface structures by replicating a model with said decorative surface structure are already known in the prior art. The methods are based on the molding of polymers, which are used as such with a decorative PVD layer, or are subsequently replicated by hot stamping of amorphous metals, as described in patent document US 5,950,704, or by galvanic growth, as shown in the accompanying drawings of this document. Figure 2 As shown. (A) A model 1 having a structure 1a is provided. (B) A polymer layer for forming a negative replica mold 2 is molded onto the structure 1a of the model 1. (C) The model 1 is removed and a conductive layer 3 is deposited on the cavity 2a of the negative replica mold 2. (D) A metal layer 4 is deposited on the surface of the replica 2 having the cavity 2a by current growth. (E) The replica 2 is removed and an object 5 is left, which is a replica of the initial model 1. Optionally, the object 5 can be repeatedly used as a model for making additional parts. The polymer negative replica mold 2 can also be the final object. Summary of the invention

[0003] The present invention aims to improve the replication method to obtain an object with a shiny polycrystalline surface, which object optionally has the appearance of a precious material. More specifically, this method is suitable for giving the surface of an object a specific shape and / or a specific optical effect for decorative and / or functional purposes.

[0004] More specifically, the present invention relates to a method for obtaining a decorative object having a shiny appearance, said method comprising the steps of:

[0005] - providing or preparing a model having a surface of the polycrystalline structure to be replicated,

[0006] - preparing a negative replica of said surface using a polymer material,

[0007] - separating the model from the negative replica,

[0008] - optionally followed by the following steps:

[0009] - preparing an object, also called a positive replica, on a replica surface of at least a portion of said negative replica,

[0010] The method is characterized in that during the above steps, one or more operations are performed to impart a specific optical effect and / or functional appearance to the decorative object, the one or more operations being selected from the following operations:

[0011] - Locally modify the polycrystalline structure of the model,

[0012] - Modify the shape of the copied negative mold,

[0013] - selectively producing solid bodies on certain parts of the replication surface of the negative replication mold,

[0014] The resulting decorative object is a negative replica, or if the optional step is performed, the solid body.

[0015] The shiny and optionally precious appearance of the object is conferred by the polycrystalline nature of the model, with a dedicated decorative effect associated with controlled variations in the growth of the crystals during the preparation of the model, or obtained by patterning of the crystals after the model has been made. The more or less precious appearance of the object will depend on the choice of the material used to replicate the positive mold and on the finishing treatments applied to the object after replication.

[0016] Other decorative effects can be obtained by giving the negative replica a specific shape or by selectively producing solid bodies on the negative replica.

[0017] Functional appearance can also be added by such specific shaping of the replica, by selectively preparing the solid or by modifying the model, such as engraving hidden data (logos, serial numbers, etc.).

[0018] Another aspect of the invention relates to an object obtained by said method. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A decorative object, in particular a watch dial, obtained using the method of the invention is shown.

[0020] Figure 2 The method of obtaining an object by replication in the prior art is schematically shown.

[0021] Figure 3 A production method according to an alternative embodiment of the invention is schematically shown, wherein the 2D shaping of the solid body is performed on a negative polymer replica mold.

[0022] Figure 4 A production method according to another alternative embodiment of the invention is schematically shown, wherein a polymer negative replica is subjected to 3D shaping. DETAILED DESCRIPTION

[0023] The invention relates to a method for obtaining a decorative object by replicating a model. The decorative object may be, for example, a piece of jewellery or an external part of a watch, such as a middle, a back, a bezel, a push-piece, a bracelet link, a flange, a dial, a hand or a dial scale. The object is characterized in that at least one of its surfaces has a shiny and optionally precious appearance. For example, Figure 1 An object 5 obtained using the method of the invention is shown, the object being in the form of a dial provided with a logo 9 .

[0024] As a preface, the method for obtaining a decorative object 5 comprises the following steps known in the prior art:

[0025] - providing or preparing a model 1 having a surface 1a of the polycrystalline structure to be replicated,

[0026] - preparing a negative replica 2 of said surface 1a using a polymer material,

[0027] - separating the negative replica 2 from the model 1,

[0028] - optionally, producing a solid 4 on at least a portion of the replication surface 2a of said negative replication mold 2,

[0029] This entity is also called the positive replica.

[0030] The decorative object 5 is a replica of a negative mold 2 or a replica of a positive mold 4 .

[0031] Model 1 with a polycrystalline structure is obtained by natural polycrystalline growth, which is also called self-assembly. This results in atomically smooth surfaces and perfect edges. For example, polycrystalline growth can be achieved by evaporation, by vacuum arc or microwave plasma generation or by thermal filamentation. In all cases, temperature is a factor used to control the crystal growth in the model.

[0032] The polycrystalline material of the model 1 can be, for example, a metal, diamond or ceramic material. As another alternative, the model can also be a component obtained from a previously prepared replica. In this case, the surface to be replicated has a crystal structure, which can also be described as a pattern of a replicated crystal structure, which is not obtained by natural polycrystalline growth. In both cases, this involves a model 1 having a surface 1a, which has a polycrystalline structure.

[0033] The body 4 can be obtained by electroforming a metal on a replica face 2a, wherein the replica face 2a has been previously coated with a conductive layer 3, by injecting the material onto a replica negative mold 2 used as an insert in the model or by stamping the material onto the replica face 2a. When the body 4 is obtained by galvanic growth, the body 4 is made of a metal or a metal alloy. If it is obtained by injection molding or stamping, it is made of ceramic, metal, polymer or composite material, wherein the metal can be amorphous. When the object 5 is a replica negative mold 2, it is made of a polymer.

[0034] According to the invention, decorative and / or functional effects are obtained on the object by one or more of the following operations, which are carried out during the manufacturing process on the model 1 , on the negative replication mold 2 or on both.

[0035] In order to obtain a specific optical effect, the operation is performed on the model 1 during its preparation or after its manufacture. During the self-assembly growth of the model 1, the growth parameters and in particular the temperature are locally changed in a controlled manner, thereby selectively changing the crystal size and / or crystal orientation on the surface of the model 1. This causes a shiny additional optical effect to improve the aesthetics. For functional and / or decorative purposes, the local change of the growth parameters can be used to engrave a logo, form a polycrystalline mosaic or any other decoration on the polycrystalline surface 1a of the model 1.

[0036] Once a model 1 with a polycrystalline structure 1a is produced, the shape of the crystal can also be modified by re-manipulating and truncating its vertices and surfaces. This can be done, for example, by selective laser etching or local machining. This can also obtain shiny additional optical effects to improve the aesthetics. This makes it possible, for example, to form holographic images. For functional purposes, it can be used to engrave hidden data that can be read with specialized optical equipment, such as individual logos, QR codes or serial numbers, etc. The shape of the crystal can be modified based on the original model 1 or a replica model 4 used as a model.

[0037] According to the present invention, operations during the preparation of the model 1 and operations after the model 1 is prepared can be combined.

[0038] Manipulations may also be performed on the polymer negative replica 2. This includes 2D, 2.5D and / or 3D shaping to improve the aesthetic appearance and / or add functionality. Shaping includes building a negative replica 2 before preparing the entity 4.

[0039] The LIGA method is used for 2D shaping of the solid body 4 on the replica negative mold 2, such as Figure 3(C) After depositing the conductive layer 3 on the surface 2a of the replica 2 (for example by PVD vacuum deposition), and before the current growth of the entity 4, (D) a photoresist layer 6 is deposited on at least a portion of the surface 2a. Selective irradiation is performed, which is performed through a previously constructed mask 7 (E), i.e., by Figure 3 The process is carried out by conventional photolithography as shown; or by laser lithography on certain parts without the need for masks. The irradiated photoresist parts are removed, or vice versa, the non-irradiated parts are removed - depending on whether the photoresist used is positive or negative; the cavity 8 is formed chemically and then the body 4 is made in the cavity 8 by electroforming (F). This makes it possible to form objects with complex contours, through holes 10, sharp edges, etc., while maintaining a shiny polycrystalline surface.

[0040] With regard to 2.5D formation, the method is substantially the same, wherein the steps of depositing a conductive layer and irradiating a photoresist layer are repeated multiple times to form layers or blind vias, etc.

[0041] Regarding 2D molding and 2.5D molding, conventional machining can also be used to add complex structures.

[0042] For 3D molding, the negative replica mold 2 must be made of a flexible polymer, such as silicone. Figure 4 As shown, and includes molding the flexible replica 2 into the desired shape and fixing it in this shape, for example by placing it on a hard substrate 11 having the desired shape (C), which can be, for example, a second hard polymer. The replica 2 can be, for example, bonded to the hard substrate 11. The shape can vary. These shapes can be arched, spherical, cylindrical, etc. Then deposit the conductive layer 3 required for current growth (D). As another option, the polymer 2 can be molded after the metal layer 3 has been deposited. Then (E) current growth is performed to obtain the entity 4. As another option, the flexible polymer replica 2 formed in this way can be used as an insert in injection molding, which is obtained by injecting ceramic or metal or any other injectable material into the mold or by stamping. This enables the production of 3D objects with shiny polycrystalline surfaces (F). For example, polycrystalline pointers, polycrystalline intermediate parts or connectors with polycrystalline structures can be produced.

[0043] The objects obtained by the various replication methods described above can then be finished by shaping processes, such as conventional machining, laser, water jet and coloring processes, for example by PVD, CVD, ALD or in the case of metal objects by galvanic growth. Vacuum deposition of thin noble metal layers (gold, gold alloys, Pt, etc.) or noble metal appearances (yellow TiN, etc.) gives the objects a noble appearance with a shiny effect. Coloring with varnish, for example, will give an entity without a noble appearance, but with a shiny effect.

[0044] In another embodiment of the invention, coloring by vacuum deposition is performed conformably on the facet of the polycrystalline structure. In the case of directional PVD, this involves normal incidence on the surface of the negative replica or solid or rotating the part, thereby achieving uniform coloring.

[0045] In another alternative embodiment of the invention, the directional nature of the PVD process, in particular evaporation, is used to color the polycrystalline surface of the replica negative mold or entity, which is carried out by metallization or deposition of a dielectric layer at oblique or grazing incidence, thereby covering the front side only in a specific orientation to obtain a specific optical appearance.

[0046] name:

[0047] 1. Model

[0048] a. Polycrystalline surface 2. Replication negative mold

[0049] a. Copy surface 3. Conductive layer

[0050] 4. Solid, also known as a replica positive mold 5. Decorative objects

[0051] 6. Photoresist layer

[0052] 7. Mask

[0053] 8. Cavity

[0054] 9. Logo

[0055] 10. Holes 11. Hard substrate.

Claims

1. A method for obtaining a decorative object (5) having a shiny appearance, the method comprising the following steps: - providing or preparing a model (1) having a surface (1a) of the polycrystalline structure to be replicated, - preparing a negative replica (2) of said surface (1a) using a polymer material, - separating the model (1) from the negative replica (2), - optionally followed by the following steps: - producing a solid (4), also called a positive replication mold, on a replication surface (2a) of at least a portion of said negative replication mold (2), The method is characterized in that: During the above steps, one or more operations are performed to impart a specific optical effect and / or functional appearance to the decorative object (5), said one or more operations being selected from the following operations: - locally modify the polycrystalline structure of model (1), - modifying the shape of the negative replica (2), - if the optional step is carried out, selectively producing the solid (4) on certain parts of the replication surface (2a) of the negative replication mold (2), The resulting decorative object (5) is a negative replica of the mold (2) or, if the optional step is carried out, a positive replica of the mold (4).

2. The preparation method according to claim 1, characterized in that The polycrystalline structure of the model (1) is modified during its preparation by locally varying the temperature of the model (1) during crystal growth.

3. The preparation method according to any one of the preceding claims, characterized in that The structure of the surface (1a) of the model (1) is modified by re-machining the shape of certain crystals after the model is made.

4. The method according to claim 1, characterized in that The shapes of some crystal vertices and surfaces of the surface (1a) of the model (1) are modified by selective laser etching or local machining.

5. The preparation method according to any one of the preceding claims, characterized in that Regarding the 2D shaping of the entity (4) on the replication surface (2a) of the negative replication mold (2), the entity (4) is selectively prepared on certain parts of the replication surface (2a) of the negative replication mold (2), and the entity (4) is prepared by the LIGA method from the following sub-steps: - depositing a conductive layer (3) on the replication surface (2a) of the negative replication mold (2), - depositing a photoresist layer (6) on the conductive layer (3), - selectively irradiating the photoresist layer (6), - removing the irradiated part of the photoresist layer (6), or removing the non-irradiated part, thereby creating a cavity (8) revealing the conductive layer (3), - Galvanic growth of the entity (4) is carried out inside the cavity (8).

6. The method according to the preceding claim, characterized in that Regarding the 2.5D forming of the entity (4) on the replication surface (2a) of the replication negative mold (2), the steps of depositing the conductive layer (3), depositing the photoresist layer (6), selectively irradiating the photoresist layer (6), removing a portion of the photoresist layer (6) and the current growth step of the entity (4) are repeated multiple times.

7. The preparation method according to any one of the preceding claims, characterized in that The replica mold (2) is molded to give a three-dimensional shape to the entity (4) during the step of preparing the entity (4), wherein the step of preparing the replica mold (2) is carried out using a flexible polymer such as silicone, and then the replica mold (2) is molded to produce the desired shape and fixed in this shape.

8. The method according to the preceding claim, characterized in that The negative replica (2) is fixed in the shape by being fixed to a rigid substrate (11).

9. The preparation method according to any one of the preceding claims, characterized in that The entity (4) is obtained by electroforming, injection molding or stamping.

10. The preparation method according to any one of the preceding claims, characterized in that The body (4) is made from a material selected from the group consisting of metals, metal alloys, ceramics, polymers and composite materials.

11. The preparation method according to any one of the preceding claims, characterized in that The method comprises the additional step of coloring the solid (4) or, if the negative replica (2) is intended to form a decorative object (5), coloring the negative replica (2); the coloring being carried out by vacuum deposition on the solid (4) or on the negative replica (2), or, if the solid (4) is metal, by galvanic growth on the solid (4).

12. The method according to the preceding claim, characterized in that The entity (4) is colored by metal deposition or dielectric deposition applied by directional PVD at oblique or grazing incidence, so that the front side of the replicated polycrystalline surface is covered only in certain directions, thereby obtaining a specific optical effect.

13. A decorative object (5) having a shiny appearance obtained using the preparation method according to any one of the preceding claims, characterized in that The decorative object (5) is a piece of jewellery or an external watch part.

14. Decorative article (5) according to the preceding claim, characterised in that External watch parts are middle pieces, dials, hands, scales or connections.

15. The decorative object (5) according to claim 13 or 14, characterized in that The decorative article includes one or more patterns, reliefs and / or non-planar shapes.

16. Decorative article (5) according to the preceding claim, characterised in that The one or more patterns and reliefs are selected from a logo (9), a holographic image, a serial number, a QR code and a hole (10).

17. The decorative object (5) according to any one of claims 13 to 16, characterized in that The decorative item also has a precious appearance.

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