HK40011757B - Production method for a trim part with decoration for watch or jewellery - Google Patents

Description

Method for manufacturing external part with decoration for watch or jewelry

Technical Field

The invention concerns the field of timepieces and jewellery. More specifically, the invention relates to a method for performing coextrusion compounding (coextrusion compounding) on a substrate, in particular for manufacturing bracelets or watch bands.

Background

Plastic watchbands with different colors, decorations or incorporating specific visual effects are highly appreciated by customers. This type of bracelet can be produced by injection moulding, overmoulding or double injection moulding of plastic materials of different colours. These are batch manufacturing processes with multiple steps, which makes them unsuitable for cost-effective industrial mass production.

In the past, watchbands have been proposed to be manufactured by an extrusion process, which is a relatively low cost process. The manufacture of watch straps by extrusion is generally limited to the manufacture of watch straps of a single colour, simple in shape and made of the same material, as described in patent FR 2121864. More recently, it has been proposed in patent application EP16150493 to co-extrude materials of different colours or properties in order to form watch bands with more complex geometries and characteristics.

However, these methods do not allow the generation of complex patterns involving specific geometries and very high precision, as is the case with landscapes, figurines, messages, etc. These methods also have difficulty integrating materials other than plastic materials that can produce unique aesthetic effects.

Generally, watch bands with complex designs are made by digital printing on a single-color substrate made by molding. Digital printing enables a wide variety of designs. However, this approach has several disadvantages: the pattern is only on the surface and is therefore subject to mechanical wear. This means that the pattern will fade away over time. The wear is often irregular, which quickly results in an unsatisfactory aesthetic appearance of the bracelet. The pattern is also susceptible to uv damage and chemical damage. Therefore, the watch band manufactured by this type of method has a pattern that changes over time, resulting in an effect of appearance that is undesirable and unattractive. Patent FR2639870 overcomes this problem by proposing a bracelet formed of a thermoplastic body, a printed film and a transparent protective layer. However, the manufacturing method proposed in this document is an injection molding process. This leads to problems in positioning and holding the printed film in place within the mold. Furthermore, the process is time consuming (printing and cutting the printed film, positioning the film in the mold, molding and forming the transparent protective layer) and requires multiple manual operations. This makes high productivity impossible.

Another disadvantage of surface printing the watch band is the insufficient adhesion of the digital printing ink to plastic watch bands of the silicone type with low surface energy. In addition, changing the base plastic formulation of the wristband typically involves readjusting the ink formulation.

Disclosure of Invention

It is an object of the present invention to manufacture an exterior part, more particularly a bracelet or wristband, with a complex pattern, using a simple and cost-effective method that is compatible with high productivity. More precisely, the invention aims to incorporate decoration within the external part and, in the case of printing inks, without any problems with positioning or ink adhesion. The invention also aims to develop a manufacturing method that guarantees the stability over time of the printed decor.

To this end, the invention relates to a method for manufacturing an external part of a watch or jewelry, in particular a watch band, comprising the following steps:

-providing a substrate having a first side opposite a second side,

-covering a first and a second strip made of synthetic material respectively on a first and a second face of said substrate by means of a coextrusion process; the first tape forms a transparent or translucent layer on the first side such that all or part of the substrate remains visible.

According to an advantageous embodiment of the manufacturing method according to the present invention, before the step of performing the coextrusion compounding of the first and second side of the substrate, a step of printing and/or etching a decoration on the first side of the substrate is provided, and preferably a plurality of different decorations are printed and/or etched one after the other on the first side of the substrate.

According to a preferred variant, the step of providing a 2D or 3D file containing customization data relating to the printing or etching of each decoration is carried out before the printing step.

Drawings

The features and advantages of the present invention will become apparent upon reading the following detailed description and upon reference to the accompanying drawings.

Fig. 1 shows a schematic view of an extruder upstream of a coextrusion die for carrying out the process according to the invention.

FIG. 2 illustrates a method for printing a plurality of series of different patterns on a blank tape. The thus decorated tape is used as a substrate in the coextrusion lamination process according to the invention.

Fig. 3 shows a schematic representation of a multilayer extrudate produced by a coextrusion die according to the invention, and a schematic representation of the extrudate after cutting and stamping. According to this variant, the bracelet is coextruded in the longitudinal direction of the bracelet. In fig. 4, another variant is shown, in which the bracelet is coextruded in the transverse direction of the bracelet. The extrudate is also shown after the cutting operation. At its lateral ends, the extrudate has a hollow tubular structure, which can be used for the subsequent attachment of the bracelet to the watch case.

Fig. 5 shows a partial perspective view of a watch with a bracelet obtained by the method of the invention, fixed to the watch case by a design of the NATO type.

Fig. 6 shows a perspective view of a watch with a watch band manufactured according to the coextrusion process of the invention. The upper band of the watch band has raised areas separated by recessed portions. Although not shown, the upper band is transparent or translucent to reveal the decoration of the central band.

Detailed Description

The invention relates to a method for covering (i.e. compounding) a substrate by means of a coextrusion process for manufacturing an external part for a timepiece or piece of jewelry. "external part" means in particular a watch band, a watch case and its constituent elements, a bezel or a dial. The method is described more specifically herein with respect to the manufacture of watchbands. The method comprises the compounding of a substrate with a complex decoration and/or texture with a tape made of synthetic material. Fig. 1 schematically shows a method of coextruding a covering synthetic material 2 on each side of a decorative band web forming a substrate 1. According to the invention, the decorative-facing coating is at least partially transparent or translucent so that the decorative pattern can be seen.

The decorative band is formed of any flexible substrate capable of withstanding high temperatures of about 200 ℃ for several seconds. The thickness of the decorative band is generally between 50 μm and 2mm, preferably between 100 and 500 μm.

The pattern may be uniform along the entire belt. For example, the decoration band can be a natural or synthetic fabric band (non-woven, unidirectional, woven, knitted), made in particular of: flax, cotton, hemp, wool, polyester fibers (dacron), polyamide fibers (chinlon) -polyurethane fibers (spandex). The decorative tape may also be a strip of photo paper, a metal sheet, an adhesive tape incorporating mineral particles (e.g. sand), organic particles (e.g. wood fibers, vegetable matter) or metal particles (e.g. gold foil). The decorative band may also be a band made of a thermoplastic elastomer, for example: TPUs, TPIs, TPE-O (thermoplastic polyolefins), TPE-S (styrenic thermoplastic elastomers), TPE-E (thermoplastic copolyesters), TPE-A (thermoplastic copolyamides) or TPE-V and TPSi-V (a combination of thermoplastic and crosslinked polysiloxanes). The decorative strip may also be a strip of PVC, PET, some type of Polycarbonate (PC), natural or synthetic rubber. The tape can be used without treatment, in which case the decoration is provided by the material itself having its natural fibrous appearance, metallic luster, etc. The tape may also be decorated by conventional printing methods, such as pad printing, silk screening, offset printing, flexographic printing, digital printing. In particular, the printing on the substrate makes it possible to incorporate within the decoration a coloured pigment, a compound having fluorescent, phosphorescent, thermochromic or photochromic properties. The tape can also be decorated by an in-line etching process of the calendering type. From an industrial point of view, this method is very suitable for manufacturing watch straps. In the same series, the watchbands have the same design and the manufacture of the new series only requires the replacement of the reel of the decorative band.

According to one variant of the invention, the pattern is printed on demand on a blank substrate tape. Thus, several series of different patterns can be printed and/or etched one after the other on the same strip 1, as shown in fig. 2. Preferably, the printing is done using digital printing to allow for greater flexibility. In this case, belts made of thermoplastic elastomers (TPE-O, TPU, TPI, TPE-S, TPSi-v, TPE-v), rubber, PET, synthetic or natural textile belts (in particular synthetic leather), etc., are particularly suitable. From an industrial point of view, this mass production method is particularly suitable for the manufacture of custom watch straps. The customer selects his/her design (drawings, personal photos, etc.) online or in the shop and can choose the type of substrate, after which the design (preferably in the form of a digital file) is processed to fit the dimensions of the substrate and then a 2D or 3D pattern is printed by digital printing on a portion of the blank substrate band, the length of said portion corresponding to the width or length of one segment of the wristband (the wristband is usually divided into two segments). Next, once the decorative band is completely printed with the respective series of patterns selected by the customer, it is covered with two strips of synthetic material. The multilayer extrudate thus formed is cut by means of a water jet, a laser, a digital knife (for example a machine supplied by the manufacturer Z und) or by means of a stamping process to produce custom watch bands.

The plastic cover tape according to the invention is intended to protect the decorative tape from external damage and to provide a particular aesthetic and/or visual appearance, for example, the plastic cover tape may be arranged to have a magnifying effect or other similar optical effect. An inner cover strip intended to be in contact with the skin and an outer cover strip on the opposite side of the substrate are provided. Typically, the thickness of these tapes is between 100 μm and 2mm, preferably between 100 μm and 1 mm.

The outer plastic cover strip is at least partially transparent or translucent and has a transmission of greater than 60% according to standard ASTM D-1003 to reveal the pattern of the decorative strip. A variety of configurations are contemplated. In a first variant, the outer band is completely transparent or translucent, thus displaying a pattern over the entire surface. In a second variant, the outer cover band is obtained by a coextrusion process performed on a plurality of mixtures of a plurality of materials of different colors or different refractive indices, at least one of which is transparent to reveal the pattern of the decoration band. Thus, for example, lines of different colors can be made across the width of the extrudate while maintaining transparent or translucent regions. This arrangement makes it possible to obtain different depth effects between the edge and the centre of the bracelet.

The inner plastic cover tape is selected to provide comfort to the customer. It has a hardness between 55 and 90Shore A and may contain additives to improve comfort. For example, it may contain a hexagonal boron nitride type ceramic to remove heat and reduce perspiration. It may also contain textile fibres with a capillary effect to wick away perspiration, or contain aluminium salts to limit perspiration. It may also contain antimicrobial agents such as silver pyrithione or zinc pyrithione particles to achieve an anti-odor effect. As with the outer band, it can be obtained by performing a coextrusion process on a plurality of plastic mixtures of different colors or different refractive indices, to provide different optical effects between the edges and the centre of the bracelet. Likewise, the present invention does not preclude the inner band from also being at least partially transparent or translucent.

According to the invention, the synthetic material used in the coextruded coating is a mixture containing at least one elastomer. Preferred elastomers are thermoplastic elastomers, polysiloxanes, rubbers and fluorinated elastomers.

More precisely, for the outer band, the elastomer is preferably chosen from the following list:

-TPE-O-thermoplastic polyolefin

TPE-S-more specifically, the styrene compound SBS, SEBS or SEPS

-TPE-E-copolyester compound

-TPE-U-thermoplastic polyurethane

-TPE-A-thermoplastic Polyamide

Ionomer resins

Polysiloxanes, and preferably MVQ (methyl vinyl silicone rubber)

-fluorinated elastomers: FKM.

More precisely, for the inner belt, the elastomer is preferably selected from the following list:

-TPE-O-thermoplastic polyolefin

TPE-S-more specifically, the styrene compound SBS, SEBS or SEPS

TPE-V-more specifically, the compounds PP/EPDM or TPSiV (combination of thermoplastic and crosslinked silicone)

-TPE-E-copolyester compound

-TPE-U-thermoplastic polyurethane

-TPE-A-thermoplastic copolyamides

Ionomer resins

Polysiloxanes, and preferably MVQ (methyl vinyl silicone rubber)

-fluorinated elastomers: FKM.

Preferably, the synthetic materials used for the inner and outer bands are chemically compatible and preferably identical, to ensure good cohesion (integral nature) of the bracelet.

Depending on the elastomer selected for its particular properties, the mixture may be supplemented with various fillers and additives as needed to improve customer comfort.

The coextrusion compounding process may include the manufacture of a multilayer extrudate 3 having a width corresponding to the width of the watch band, as shown in fig. 3. Advantageously, the width of the base material 1 is smaller than the width of the upper and lower bands 2, so that its side edges are completely covered by the synthetic band. The coextrusion lamination process may also include the manufacture of a multilayer extrudate 3 having a width corresponding to the length of one segment or both segments of the watch band, as shown in fig. 4. Likewise, the side edges of the substrate are completely covered with synthetic material. According to the embodiment of fig. 3, the shape of the bracelet 5 and the required holes 6 are obtained by punching, laser cutting, digital knife cutting or water jet cutting. The multilayer extrudate obtained after coextrusion can be integral and attached to the watch case 8 by means of a ring 7 arranged on each side of the case; this is the so-called NATO design shown in figure 5. According to the embodiment of fig. 4, in order to facilitate the subsequent assembly of the bracelet to the watch case, it is advantageous to make the multilayer extrusion 3 comprising, at its lateral ends, protruding hollow tubular structures 9, the hollow tubular structures 9 being intended to receive rods for attachment to the watch case by means of buckles and lugs, the required width of the bracelet previously being obtained by laser cutting, digital knife cutting, water jet cutting or punching. It is also conceivable to produce a multilayer extrusion which incorporates the profile of the watch case surrounded by the bracelet segments over the entire width. The recess for the watch case can then be formed by stamping.

It should also be noted that the coextrusion die may have a unique profile for extruding a cover tape having protruding areas or, more generally, a specific embossed design. Figure 6 shows the profile that can be obtained for an external band, such as a watchband. Other advantages of the extrusion method can also be obtained without departing from the scope of the invention, such as combining materials to locally modify the mechanical properties of the bracelet (in particular, for example, the attachment means).

The watch band produced by the coextrusion process in this way has a number of advantages.

The method according to the invention is a cost-effective mass production method that makes it possible to obtain a customized wristband with a design chosen by the customer, or to obtain a unique wristband. Therefore, this is different from the one-piece molding method which is not suitable for mass production at high productivity.

Very different designs can be obtained without changing the production line.

These watchbands have a particular aesthetic appearance, i.e. with a depth effect and a three-dimensional effect, produced by a thick transparent synthetic material layer.

The complex pattern is located on the inside of the wristband. Thus, the synthetic tape can protect the pattern from external damage (mechanical abrasion, chemical damage, ultraviolet rays, etc.). The pattern is printed on a flat substrate rather than on a three-dimensional surface strip, which also greatly simplifies the printing process.

Unlike the injection molding process, the method according to the invention allows the decorative band to be positioned precisely within the synthetic material.

The nature of the decorative band can be chosen to ensure good adhesion of the ink, regardless of the basic formulation of the bracelet.

Further, the cohesion of the band is ensured by the adhesion/attachment between the upper and lower bands without worrying about the adhesion property between the decorative band and the cover band. These features make it possible to integrate any type of media, including textiles, in the external component.

Parts list

(1) Base material, also called decorative tape

(2) Outer and inner bands

(3) Extrudate

(4) Printing machine

(5) Bracelet or watch strap

(6) Hole(s)

(7) Ring (C)

(8) Watch case

(9) Hollow tubular structure

(10) Watch (watch)

Claims (14)

1. A method for manufacturing an external part for a watch or jewelry, comprising the steps of:

-providing a substrate (1) having a first side opposite a second side,

-co-extrusion coating the first and second faces of the substrate (1) with first and second strips (2) made of synthetic material, respectively, so that the side edges of the substrate are completely covered by the first and second strips; the first tape (2) forms a transparent or translucent layer on the first face, so that all or part of the substrate (1) remains visible,

wherein, prior to the co-extrusion coating step, a decoration is printed and/or etched on the first side of the substrate (1),

the substrate (1) is formed from a natural or synthetic fabric tape, a photographic paper tape, a metal tape, a thermoplastic elastomer tape, a rubber tape or an adhesive tape.

2. Method according to claim 1, characterized in that the external part is a bracelet or watch strap (5).

3. Method according to claim 1 or 2, characterized in that a plurality of different decorations are printed and/or etched one after the other on the first side of the substrate (1).

4. A method according to claim 3, characterised in that before printing, the method comprises a step of providing a 2D or 3D file containing customization data relating to the printing or etching of each decoration.

5. The method according to claim 1 or 2, characterized in that the substrate (1) comprises a material selected from the following list: flax, cotton, hemp, wool, synthetic leather, polyester, polyamide, polyurethane, thermoplastic polyolefin (TPE-O), Thermoplastic Polyimide (TPA), Thermoplastic Polyurethane (TPU), styrenic thermoplastic elastomer (TPE-S) or thermoplastic copolyester (TPE-E) or thermoplastic copolyamide (TPE-A) rubber, polyvinyl chloride.

6. The method of claim 5, wherein the polyester is PET.

7. Method according to claim 1 or 2, characterized in that the adhesive tape comprises mineral, organic or metallic particles.

8. Method according to claim 1 or 2, characterized in that the printing enables the incorporation of coloured pigments, luminescent compounds, thermochromic compounds, photochromic compounds, or mixtures of the aforementioned in the decoration.

9. The method according to claim 1 or 2, characterized in that the width of the base material (1) is smaller than the width of the first and second strips (2) in order to be covered by said strips in a co-extrusion coating step.

10. Method according to claim 1 or 2, characterized in that the first and/or second strip (2) made of synthetic material is obtained by performing a co-extrusion process on several mixtures of several synthetic materials having different colours and/or refractive indices and/or mechanical properties.

11. Method according to claim 1 or 2, characterized in that the synthetic material of the first and second belt (2) is selected from thermoplastic elastomers and rubbers.

12. The method of claim 11, wherein the thermoplastic elastomer is a polysiloxane or a fluorinated elastomer.

13. Method according to claim 1 or 2, characterized in that the synthetic material of the second belt (2) comprises a filler for improving the comfort of the outer part.

14. A method as claimed in claim 2, characterised in that the width of the extrudate (3) produced by the coextrusion coating process corresponds to the width of the bracelet strand (5) or to the length of one or both segments of the bracelet strand (5).