CH716891A2 - A method of marking a decorative article. - Google Patents

Abstract

The present invention relates to an in-line method of marking an extruded synthetic material substrate (1), said method comprising the steps of: Extruding the synthetic material through an extrusion die (3) to form the substrate (1), Mark said substrate (1) by scrolling the substrate (1) from the extrusion die between two rollers (2a, 2b) mounted to rotate and thermoregulated with an upper roller (2a) and a lower roller (2b ), one of said rolls having an imprint (5) forming the negative of a decoration or a texture to be marked on one face of the substrate (1), this same roll or the other of said rolls comprising at least one notch (6 ) making it possible to guide the substrate (1) as it passes through the extrusion die and between the two rollers (2a, 2b). The substrate may be intended to make a watch or jewelry strap. The present invention also relates to the installation comprising in line the extrusion die (3) and the marking device (2).

Description

Technical area

The present invention relates to a method of online marking of a synthetic material substrate directly from an extrusion die.

Technological background

To mark plastics, several methods are known and used. Mention may be made of embossing, laser engraving or even traditional printing methods.

Laser engraving is the most widely described method for marking plastics. It has several advantages such as durability and flexibility of the pattern to be engraved. On the other hand, the equipment is very expensive and most importantly the majority of plastics cannot be labeled effectively without the use of sensitive laser additives. The selection of additives and the type of laser is not easy and requires a large number of tests for each plastic formulation.

The inkjet and digital printing processes are compatible with online customization of a profile and allow the printing of various patterns. On the other hand, the marking wears out over time and is therefore not durable.

Embossing consists in passing the molten material between heated rolls to produce a flat film, the latter then passing between rolls engraved with a pattern. This process described, for example, in document US Pat. No. 4,744,936 thus only makes it possible to obtain marked films having a constant thickness. It is not suitable for marking profiles of complex shape with varying thicknesses such as in the case of watch straps.

Summary of the invention

To overcome the aforementioned drawbacks, the present invention provides a new marking process which makes it possible to etch both substrates of simple shape and substrates of complex shape, which makes it possible to achieve lasting marking while being inexpensive. This process can be advantageously used to decorate, personalize or even carry out an anti-counterfeiting marking on a section made of synthetic material.

[0007] More specifically, the method according to the invention is an online method for marking a substrate made of extruded synthetic material, comprising the steps consisting in: Extrude the synthetic material through an extrusion die to form the substrate, Mark said substrate by scrolling the substrate from the extrusion die between two rotatably mounted and thermoregulated rollers with an upper roller and a lower roller, one of said rollers having an imprint forming the negative of a decoration or a texture to mark on one face of the substrate, this same roller or the other of said rollers comprising at least one notch making it possible to guide the substrate as it passes through the extrusion die and between the two rollers.

Preferably, the notch is intended to receive the substrate over its entire width.

[0009] According to one variant, the notch is intended to receive a portion of the width of the substrate. For example, this portion may consist of a relief present at the end of the extrusion process and intended to be housed in the notch of complementary shape.

Advantageously, the method according to the invention comprises a forced cooling step between the extrusion step and the marking step so as to fix the profile of the extruded substrate while maintaining a certain deformability of the material so as to allow its marking.

[0011] After the marking, the substrate is sized using a mechanical stamping tool, by water jet, laser or ultrasound cutting in order to obtain the desired decorative article.

This marking method has the advantage of being in line with the extrusion method, which makes it possible to mask the marking time and therefore to reduce the cost.

[0013] The general profile of the substrate is not modified during the marking which makes it possible to preserve the dimensions of the profile resulting from the extrusion and to mark any type of profile.

An infinite number of patterns and textures can be produced via this process, including micrometric textures to avoid counterfeiting. In addition, the marking obtained by this process does not deteriorate over time. It is also very fine and precise.

Compared to an injection process, this process combining extrusion and marking has several advantages: It is an in-line process, that is to say a process which allows high productivity compared to a batch process such as that of injection. The customization of the pattern or the texture is done at a lower cost because the investment for a pair of rollers is significantly less than for an injection mold.

The present invention also relates to the installation comprising in line the extrusion die and the marking device.

Brief description of the figures

The invention will be described below in more detail with the aid of the accompanying drawings, given by way of non-limiting examples, in which: FIG. 1 diagrammatically represents the continuous line of manufacture of decorative articles including the extrusion die and the marking device separated by cooling means. FIG. 2a shows a three-dimensional view of the marking device provided with an embossing roller and a backing roller comprising a notch according to the invention. FIG. 2b represents a partial sectional view along the plane A-A. FIG. 3 represents a partial sectional view along the same plane A-A of a variant of the marking device. FIG. 4 represents a perspective view of two bands at the end of the extrusion with respectively at one or at each lateral end of the band a hollow tubular structure. FIG. 5 represents a partial sectional view along the same plane A-A of another variant of the marking device. FIG. 6 represents a bracelet strand extruded and marked according to the method of the invention.

Detailed description of the invention

The present invention relates to a process for marking a substrate resulting from an extrusion process. The marking method according to the invention makes it possible to engrave synthetic profiles in line in order to obtain various patterns and / or surface texturing. The process is more specifically described for the marking of a watch or jewelery trim part and in particular for the marking of a watch strap or a piece of jewelry. It can however be applied to the marking of any extruded substrate with a view to producing a decorative article.

According to the present invention, the marking is carried out on a synthetic substrate 1 using a marking device 2 which is in line with an extrusion die 3 as shown diagrammatically in FIG. 1. Preferably, the The installation comprises, between the outlet of the extrusion die 3 and the marking device 2, cooling means 4 such as a water tank or a tunnel provided with an air jet which allows the substrate to be cooled slightly after the extrusion so as to fix the profile. The installation also comprises after the marking device cutting means (not shown): water jet, ultrasound, laser or even a mechanical stamping tool to lead to the final object.

The marking device 2 comprises two rollers 2a, 2b rotatably mounted and thermoregulated. According to the invention, one of the rollers, the upper roll 2a in the example illustrated in FIGS. 2a and 2b, comprises an imprint 5 in relief and / or recessed representing a pattern (letters, numbers, drawings, etc.) or a texture intended to produce the marking 8 on one face of the substrate 1. According to the invention, this same roller 2a or the other roller 2b comprises at least one notch 6 extending over the entire circumference of the roller. This notch is used to guide the substrate during extrusion and marking. Different configurations for the positioning and size of the notches are possible.

According to the preferred variant shown in Figures 2a and 2b, the roller 2b opposite to that 2a comprising the indentation 5 comprises a notch 6 which is the width of the extruded strip 1. This notch has a depth less than or equal to the maximum thickness of the extruded strip. It is also conceivable that its depth is greater than the thickness of the strip if the imprint on the opposite roll is in relief.

[0022] According to another variant, one of the rollers has one or more notches with a width less than that of the strip. Such examples are illustrated in Figures 3 and 5. In Figure 3, one of the rollers, the upper roller 2a with the indentation 5 in the example illustrated, comprises two notches 6 respectively on either side of the indentation. 5. During the marking, the deformable material is positioned in the notches 6 and ensures the maintenance of the substrate 1. This material in the notches forms either the lost material intended to be cut, or a raised area which is maintained on the final object. Thus, FIG. 5 represents a configuration with a single notch 6 disposed opposite the cavity 5 on the same roller 2a. The material filling the notch forms a relief which is maintained on the final object. It is also possible to position the notch opposite the imprint on the other roller. It is also conceivable that one or both notches have a shape corresponding to a relief of the substrate resulting from the extrusion. Thus, in the case of a bracelet, the strip resulting from the extrusion may have a width corresponding to the length of one strand or of both strands of the bracelet. Reference is made to the EP application for this embodiment. As illustrated in FIG. 4, the extruded strip 1 comprises at one or each of its lateral ends a projecting hollow tubular structure 7. The hollow tubular structures form through holes intended to respectively receive a bar allowing attachment to the horns of 'a watch box or a buckle.

In addition to the notch (s) having a shape complementary to the reliefs present on the extruded strip, the roll (s) may have a profile adapted to variations in thickness of the strip coming from the extrusion die so as to maintain the profile at the exit of the marking device.

According to the invention, the synthetic materials used during the extrusion are mixtures comprising at least one thermoplastic polymer. Preferably, the mixture comprises at least one thermoplastic elastomer (TPE) chosen from the following list: TPE-O - Thermoplastic olefins TPE-S - Compound SBS, SEBS or styrenic SEPS TPE-V - Compound PP / EPDM vulcanized TPE-E - Compound of copolyester TPE-U - Thermoplastic polyurethane TPE-A - Thermoplastic polyamide.

The method takes place as follows. The strip is extruded through the extrusion die. It then passes through the cooling means so as to fix the dimensions of the profile while maintaining a deformable material capable of being marked and, where appropriate, capable of filling the notch or notches. On leaving the cooling means, the material typically has a temperature of the order of 50-80 ° C. By way of example, for a TPE-S strip, the material has a temperature of 180 ° C at the outlet of the extrusion die and a temperature of 70 ° C at the outlet of the cooling means. The still hot extruded strip then passes between the two rollers of the marking device. The pattern or texture of one of the rolls is then transferred to the web. The marking depth is controlled by the pressure imposed between the two rollers and the engraving of the roll. The marked substrate is then dimensioned using a mechanical stamping tool, by water jet, laser or ultrasound cutting to obtain the decorative article. By way of example, a bracelet strand extruded and marked with the method according to the invention is shown in FIG. 6.

Legend

[0026] (1) Substrate or extruded strip (2) Marking device a. Upper roller b. Lower roller (3) Extrusion die (4) Cooling means (5) Footprint (6) Notch (7) Protruding hollow tubular structure (8) Marking

Claims (18)

1. An in-line method of marking a substrate (1) of extruded synthetic material, said method comprising the steps of: - Extrude the synthetic material through an extrusion die (3) to form the substrate (1), - Mark said substrate (1) by scrolling the substrate (1) from the extrusion die between two rollers (2a, 2b) rotatably mounted and thermoregulated with an upper roller (2a) and a lower roller (2b), a said rolls having an imprint (5) forming the negative of a decoration or a texture to be marked on one face of the substrate (1), this same roll or the other of said rolls comprising at least one notch (6) making it possible to guide the substrate (1) as it passes through the extrusion die (3) and between the two rollers (2a, 2b). 2. Method according to claim 1, comprising a forced cooling step between the extrusion step and the step of marking the substrate (1), said substrate having a temperature greater than or equal to 50 ° C at the end of the process. forced cooling. 3. Method according to claim 1 or 2, comprising after the marking step, a step of dimensioning the substrate (1) to produce a decorative article. 4. Method according to one of the preceding claims, characterized in that the notch (6) has the width of the substrate (1) with said substrate (1) being positioned within the notch (6). 5. Method according to claim 4, characterized in that the notch (6) has a thickness equal to or less than the maximum thickness of the substrate (1). 6. Method according to claim 4, characterized in that the notch (6) has a thickness greater than the maximum thickness of the substrate (1) if the imprint (5) is in relief. 7. Method according to one of claims 1 to 3, characterized in that the notch (6) has a width less than the width of the substrate (1). 8. Method according to claim 7, characterized in that said same roller or the other of said rollers has two notches (6). 9. Method according to claim 8, characterized in that the two notches (6) are respectively arranged on either side of the imprint (5). 10. The method of claim 7, characterized in that the notch (6) has a shape complementary to a relief present on the substrate (1) from the extrusion die (3). 11. The method of claim 10, characterized in that the substrate is intended to make a watch or jewelry bracelet and in that the notch (6) has a shape complementary to a hollow tubular structure (7) of the substrate ( 1), the hollow of the hollow tubular structure (7) forming a through hole intended to receive a bar allowing it to be attached to the horns of a watch case or to a buckle. 12. The method of claim 11, characterized in that said same roller or the other of said rollers comprises two notches (6) having a shape complementary to two hollow tubular structures (7) of the substrate (1). 13. The method of claim 7, characterized in that the imprint (5) and the notch (6) are arranged on the same roll with the imprint (5) facing the notch (6). 14. Installation comprising an extrusion die (3) of a substrate (1) and following the extrusion die (3) a marking device (2) of the substrate (1), the marking device ( 2) comprising two rollers (2a, 2b) mounted to rotate and thermoregulated with an upper roller (2a) and a lower roller (2b), one of said rolls having an imprint (5) forming the negative of a decoration or a texture to be marked on one face of the substrate (1), this same roller or the other of said rollers having at least one notch (6) making it possible to guide the substrate (1) as it passes through the extrusion die (3 ) and the marking device (2). 15. Installation according to claim 14, comprising cooling means (4) between the extrusion die (3) and the marking device (2). 16. Installation according to claim 14 or 15, characterized in that the notch (6) has the width of the substrate (1). 17. Installation according to claim 14 or 15, characterized in that the notch (6) has a width less than the width of the substrate (1). 18. Installation according to claim 17, characterized in that the notch (6) has a shape complementary to a relief intended to be present on the substrate (1) coming from the extrusion die (3).