Method for attaching a marking composition to a substrate

Abstract

The invention relates to a method for attaching, by means of laser irradiation, a marking composition to a substrate, the marking composition comprising at least one colouring agent, the method comprising the following steps: - depositing (102) the marking composition on at least one portion of the substrate (4); - attaching (104) one part of the marking composition by moving a laser beam in order to irradiate at least one part of the marking composition deposited on the substrate, characterised in that the laser beam has a power density of between 32 W / mm² and 7.7 kW / mm² when it comes into contact with the irradiated marking composition and in that the laser beam is moved at a speed, measured with respect to the substrate, of between 10 m.s-1 and 9.0 m.s-1.

Description

METHOD FOR FIXING A MARKING COMPOSITION ON A SUBSTRATE TECHNICAL FIELD OF THE INVENTION

[0001] The present invention generally relates to a method of laser bonding a marking composition to a substrate.

[0002] More particularly, it relates to a method for fixing a marking composition on a fragile substrate such as in particular an organic substrate of plant origin, an organic substrate of animal origin, a substrate of synthetic origin (for example comprising plastic), a substrate made from cellulose such as cardboard or paper.

[0003] It also relates to a method of fixing a marking composition to a metal or plastic layer of a substrate. STATE OF THE ART

[0004] Hot stamping processes are known for marking leather substrates. These processes involve iron systems that are pressed onto the leather to be marked. These processes are functional but do not allow for marking with pigments. In addition, these processes locally damage the substrates, which can affect their properties such as their water resistance, hydrophilicity, or phobia. Finally, these processes do not allow for easy customization of patterns on the substrates.

[0005] Laser marking processes are also known on hard substrates selected, for example, from metal, plastic, ceramic, or glass. These processes are functional, but cannot be used for soft or flexible substrates that could be described as fragile due to their susceptibility to being easily scratched or damaged by heating. Indeed, in these processes, the characteristics of the laser beam used to irradiate the substrate produce heating greater than 500°C due to the light-material interaction between the laser beam and the substrate. Such a characteristic is suitable for hard substrates such as metal, plastic, ceramic, or glass, but is not suitable for more fragile substrates such as leather, textiles, or cardboard, because the heating of the material induced in this process would cause damage to these substrates by a pyrography phenomenon leading to local carbonization of the substrate.Such local carbonization is incompatible with the production of marking in colors other than. black and induces a substantial local alteration of the properties of the substrate, in particular its behavior in water.

[0006] There are also known methods for marking a metal layer on a substrate. These methods are functional but do not allow for very good adhesion of the marking composition to the metal layer. In addition, the colors obtained on a metal layer are dull, so these methods do not allow for good rendering of the color fixed on the metal layer. These methods also take longer to implement.

[0007] The aim of the invention is to remedy at least one of the aforementioned drawbacks in order to propose a fixing method which is suitable for marking a marking composition on substrates of different types, for example fragile and in particular of organic origin or metallic and plastic substrates. PRESENTATION OF THE INVENTION

[0008] To this end, the invention proposes a method for fixing by laser irradiation a marking composition on a substrate, the marking composition comprising at least one coloring agent, method comprising the following steps: - depositing the marking composition on at least a portion of the substrate; - fixing a portion of the marking composition by moving a laser beam to irradiate at least a portion of the marking composition deposited on the substrate - removal of non-irradiated marking composition at the fixation stage. According to the invention, the laser beam has a power density of between 32 W / mm 2 and 7.7 kW / mm 2 in contact with the irradiated marking composition and the movement of the laser beam is carried out at a speed, measured relative to the substrate, of between 10 millimeters per second and 9.0 meters per second (ms _ 1 ).

[0009] In the context of the invention, the displacement speed corresponds to the displacement speed relative to the substrate of the spot or spot of the laser beam on the substrate.

[0010] Power density is the amount of power that passes through a surface per unit of that surface. It therefore quantifies the power received over a portion (area) of the surface.

[0011] Thanks to the invention, it is possible to fix coloring agents of various colors on fragile substrates without altering them, unlike hot stamping techniques. Such a process is also easy to implement and allows for the creation of personalized designs more easily.

[0012] It should be noted that the combination of power density and scanning speed, according to the invention, makes it possible to limit the amount of power, per unit area, received by the substrate during its irradiation. Surprisingly and contrary to what might have been expected, this limitation of irradiation does not prevent optimal fixing of the marking composition on fragile substrates.

[0013] The removal step allows cleaning of the portions of the substrate covered by the marking composition which were not fixed in the fixing step.

[0014] In one embodiment, the power density is between 60 W / mm 2 and 5 kW / mm2 and in that the movement of the laser beam is carried out at a speed of between 0.1 m. s -1 and 9.0 m. s -1 , which further limits damage to the substrate while still providing very good marking performance.

[0015] In the present disclosure, laser beam means a light beam emitted by a laser or a laser element. Coloring agent means an agent comprising at least one pigment or at least one dye or a mixture thereof.

[0016] In one embodiment, the power density is between 430 W / mm 2 at 1.1 kW / mm 2 and the laser beam moving speed is between 2500 mm / sec and 7000 mm / sec. The method according to the present disclosure is therefore faster while achieving the same performance.

[0017] In one embodiment, the power density is between 480 W / mm 2at 1.1 kW / mm 2 and the laser beam travel speed is between 3300 mm / sec and 7000 mm / sec. Such characteristics help to minimize substrate heating and therefore its possible damage.

[0018] In one embodiment, the power density is between 480 W / mm 2 at 550 W / mm 2 and the laser beam travel speed is between 4900 mm / sec and 7000 mm / sec. Such characteristics allow for no heating of the substrate. Therefore, no changes to the substrate are made (no material damage, the substrate is preserved).

[0019] In a preferred embodiment, the power density is between 60 W / mm 2 and 5 kW / mm 2 and the movement of the laser beam is carried out at a speed between 0.1 meters per second and 9.0 meters per second (m.s' 1). Such features allow for better results while limiting the amount of power received by the substrate.

[0020] In one embodiment, the movement of the laser beam is carried out at a speed of between 0.6 and 9.0 meters per second.

[0021] Such a feature further reduces the exposure of the substrate to the laser beam, and therefore limits the risk of damaging the substrate without affecting the quality of the fixation.

[0022] In one embodiment, the laser beam has a power density of between 1 kW / mm 2 and 5 kW / mm 2 in contact with the irradiated marking composition.

[0023] Such a feature allows the use of very fast scanning speeds, which reduces the process completion time.

[0024] Within the scope of the invention, the displacement of the laser beam relative to the substrate can be carried out in any suitable manner and for example by at least one of the following displacements: - movement of the laser beam (i.e. laser scanning), - displacement of the substrate, - combination of laser beam displacement and substrate displacement.

[0025] In one embodiment, after the removal step, the marking composition covers at least ninety percent of the irradiated substrate.

[0026] In one embodiment, the surface of the substrate has a roughness of between 0 micrometers and 2 millimeters.

[0027] Thus the process works on different types of substrate, smooth or rough.

[0028] In one embodiment, the substrate is planar or curved.

[0029] In one embodiment, the method comprises a step of air drying the marking composition before the irradiation step, said drying step preferably being of a duration of less than 2 minutes.

[0030] In one embodiment, the laser is coupled with a focusing device having a focal length for focusing the laser beam into a focal point. The substrate is then located at the focal point or at a distance from the focal point of less than 5 cm and preferably less than 1 cm.

[0031] The combination of the power and beam speed characteristics with such focusing makes the fixation effective even on substrates with a flat or non-flat shape. A substrate with a non-flat shape is understood to mean, in particular, a substrate whose face to be marked is curved. or a substrate whose face to be marked has flat parts and non-flat parts and / or an irregular surface such as a substrate having concave and convex areas for example. Thus, the method is configured to fix the marking composition on substrates or parts of the substrate positioned at the focal point, for example when the substrate or the part of the substrate used is flat, or on substrates or parts of the substrate offset from the focal point, in particular when the substrate or the part of the substrate is curved, of non-planar shape.

[0032] Furthermore, working outside the focal point allows the laser power density to be reduced when in contact with the substrate. Therefore, these characteristics offer an easy-to-implement solution for fixing coloring agents on fragile substrates without the need to flatten the surface to be marked.

[0033] In one embodiment, the fixing is carried out on a face (or surface) of the substrate, called the marking face, comprising a metal layer, the method comprising, before the deposition step, a step of treating at least one area of ​​the metal layer by laser irradiation, the deposition and fixing steps being carried out on the treated area of ​​the metal layer.

[0034] In this embodiment, the metal layer may form a markable surface of the substrate.

[0035] In this embodiment, the metal layer may comprise at least one layer of at least one of the following materials: - a metal, for example a pure metal (such as zinc, aluminum, copper, gold, silver) or a treated metal (for example anodized aluminum); - a metal alloy (for example brass, steel or stainless steel, ferrous metals, zamak type alloy (alloy of zinc, aluminum and optionally copper).

[0036] Thus, thanks to the method according to the invention, it is possible to fix the marking composition on different metallic materials.

[0037] In this embodiment, the metal layer may be covered with a protective layer. The protective layer may comprise at least one of the following elements: an anodizing layer, a lacquering (for example a layer obtained by ink printing, screen printing, a paint), galvanizing, metallizing, plasticizing (for example epoxy type). In the following, when the protective layer comprises a lacquering, a galvanizing, a metallizing, a plasticizing, the latter is called lacquered metal.

[0038] Thus, when the fixing method is implemented on a metal layer, the method according to the invention may comprise a treatment step which makes it possible to transform or prepare the surface of the metal layer before the deposition and fixing of the marking composition. Such a step, combined with the properties of the laser used in the fixing step, makes it possible to obtain very good fixing of the marking composition on the metal layer as well as very good rendering of the color of this marking composition on the metal layer. In addition, the optical properties of the laser also make it possible to implement the fixing method more quickly on a substrate having a metal layer.

[0039] In this embodiment, the processing step may use a laser emitting a laser beam, wherein the laser beam used in the processing step and the laser beam used in the fixing step may have at least one identical property, wherein the at least one property comprises at least one of the following: - wavelength; - power density; - movement speed; - a number of passages.

[0040] Such a characteristic makes it possible to use the same laser in the processing and fixing stages, which makes it possible to limit the costs of implementing the method according to the invention.

[0041] In this embodiment, the processing step may be performed with a laser having a power density less than or equal to (preferably less than) the power density of the laser used in the attachment step and moving the laser beam, relative to the substrate, at a speed less than or equal to (preferably less than) the speed of movement of the laser beam used in the attachment step. For example, the power density is between 955 W / mm 2 and 1.9 kW / mm 2 (preferably between 955 W / mm 2 and 1.7 kW / mm 2 ) and the movement speed is between 500 mm / s and 1600 mm / s (preferably between 500 mm / s and 1500 mm / s).

[0042] In this embodiment, the processing step may comprise at least one of the following processes: - anodization; - laser ablation; - laser engraving; - mechanical ablation.

[0043] In this embodiment, the treated area may have, after treatment, a surface having one of the following colors: - a white color; - a gray color.

[0044] In this embodiment, in particular in the case of a substrate with a colored anodized alumina layer, the treatment step can make it possible to at least partially eliminate the anodized layer to expose the white or gray colored alumina layer.

[0045] Thus, in the present invention, lightening the color of the metal plate improves the adhesion of the coloring agent to the metal plate.

[0046] In this embodiment, the color of the surface of the treated area may depend on at least one of the following parameters: - laser power density; - the speed of movement of the laser beam; - a number of passages of the laser beam.

[0047] It is therefore possible to adapt the above parameters for a treated area of ​​desired color.

[0048] In this embodiment, during the treatment step, a laser beam may be configured to irradiate the treated area only once.

[0049] Of course, in one embodiment, the fixing is carried out on a face of the substrate, called the marking face, comprising a metal layer, the deposition step being able to be carried out on the marking face (also called the marking surface). Thus in this case, no pretreatment is carried out.

[0050] In one embodiment, during the fixing step, said laser is configured to pass n times over said part of the marking composition, with n greater than or equal to 2.

[0051] Such a feature makes it possible to limit damage to the substrate illuminated by the laser beam while obtaining a substrate having the aforementioned advantages.

[0052] In one embodiment, n is between 2 and 20, preferably between 3 and 10.

[0053] In one embodiment, the number of passes depends on the nature of the substrate. Thanks to the invention, very good results are obtained when n is equal to 3.

[0054] According to the invention, the laser used in the fixing step is continuous or pulsed.

[0055] In one embodiment, the laser used in the fixing step and / or in the processing step is a solid-state or gas-based (such as CO2) amplifying medium laser. In the present invention, a solid-state laser means a laser in which the amplifying medium comprises a crystal. For example, a solid-state laser may comprise a laser diode, a YAG laser, or a fiber laser.

[0056] Thus, the laser used in the fixing and / or treatment step can be at least one of the following lasers: - a YAG laser emitting a laser beam at an emission wavelength of 1064 nanometers, - a CO2 laser emitting a laser beam at an emission wavelength of 10600 nanometers, - a YAG laser emitting a laser beam at an emission wavelength of 532 nanometers, - a YAG laser emitting a laser beam at an emission wavelength of 355 nanometers.

[0057] Alternatively or in combination, the laser used in the fixing and / or processing step may be a doubled or tripled YAG laser emitting a laser beam at an emission wavelength between 100 nm (UV) and 1 pm (far infrared), for example 532 nm or 355 nm or 266 nm.

[0058] The method according to the invention therefore works with commonly used and widely commercially available lasers, improving the ease of implementation of the method at a reasonable cost.

[0059] In one embodiment, when the laser beam is a YAG laser, the generated laser beam is a pulsed laser beam, and when the laser beam is a CO2 laser, the generated laser beam is a continuous laser beam.

[0060] In one embodiment, the beam has a minimum diameter of between 70 micrometers and 120 micrometers, for example when the laser beam is in contact with the substrate.

[0061] In one embodiment, the processing step may be performed with a CO2 laser emitting a laser beam at an emission wavelength of 10600 nanometers and having a power density of between 955 W / mm 2 and 1,277 kW / mm 2 and a travel speed between 500 mm / s and 900 mm / s.

[0062] In one embodiment, the processing step may be performed with a YAG laser emitting a laser beam at an emission wavelength of 355 nanometers and having a power density of between 1.0 kW / mm 2 and 1.9 kW / mm 2 (preferably 1.7 kW / mm 2 ) and a travel speed between 1000 mm / s and 1600 mm / s (preferably 1500 mm / s).

[0063] In one embodiment, the marking composition comprises: - an aqueous base; - at least one coloring agent in the aqueous base.

[0064] Typically, this coloring agent may be dissolved, or be a mixture of pigments or a mixture of dissolved dyes.

[0065] In one embodiment, the coloring agent or marking composition has photochromic properties and / or thermochromic properties.

[0066] In the present disclosure, the term "photochromic element" means an element capable of changing color depending on the received light intensity. Thus, a variation in received light intensity causes a change in color. The term "thermochromic element" also means an element capable of changing color depending on the temperature. Thus, a variation in the temperature of the environment in which the element is positioned causes a change in color.

[0067] In one embodiment, when the coloring agent comprises at least one pigment, each pigment is in the form of particles of size between 10 nm and 0.1 mm.

[0068] In one embodiment, the aqueous base is 50% to 84% by weight in the marking composition.

[0069] In one embodiment, the coloring agent is at a level of 16% to 50% in the marking composition.

[0070] In one embodiment, the aqueous base is liquid.

[0071] Using such an aqueous liquid base as a vehicle for the coloring agents and particles constituting the marking composition provides a solution that improves the ergonomics of the implementation as well as the safety of the process. Indeed, in a liquid base, the particles of the coloring agent are dispersed.

[0072] In one embodiment, the aqueous base comprises water with a short chain alcohol or acrylic binder mixed with a surfactant.

[0073] Such a formulation of the marking composition allows, on the one hand, to increase the homogeneity and stability of the suspension constituting the marking composition and, on the other hand, to improve the fixation of the coloring agents on the substrate. The quality of the marking as well as its longevity are therefore improved.

[0074] Binder means an emulsion of water and acrylic resin or vinyl resin.

[0075] In one embodiment, the aqueous base does not include an organic solvent. It is thus possible to avoid the use of organic solvents which are flammable and toxic to humans and the environment.

[0076] In one embodiment, the aqueous base comprises an organic solvent.

[0077] In a variant of this embodiment, said coloring agent is in the form of particles of size between 10 and 50 micrometers.

[0078] These characteristics improve the fixation of the coloring agent at the fixation stage. In addition, such a particle size is less dangerous for humans (in case of inhalation or ingestion).

[0079] In one embodiment, the at least one coloring agent is arranged not to change color after the fixing step.

[0080] In one embodiment, the coloring agent is chosen from: - a pigment comprising at least one of the following elements: a metal oxide, a metal, a metal alloy, a metal alloy oxide; - an inorganic pigment; - an organic pigment; - a pigment comprising a carbonate mineral; - sodium aluminosilicate thiosulfate; - a synthetic colorant; - a natural colorant; or mixtures thereof.

[0081] In one embodiment, when the coloring agent is a pigment, the coloring agent may be in particulate form.

[0082] In one embodiment, the white inorganic pigment comprises TiC.

[0083] In one embodiment, the inorganic pigment comprises at least one of the following: white organic pigment, complex inorganic pigment, colored natural inorganic pigment.

[0084] In one embodiment, the pigment comprising a metal oxide may include a synthetic pigment colored in metal oxide.

[0085] In one embodiment, the organic pigment may comprise TiO2 and / or a polyoxymethylene melamine-based thermochromic pigment.

[0086] Using a coloring agent based on inorganic material allows for very good color quality. In addition, this type of coloring agent has ecological advantages.

[0087] Using a sodium aluminosilicate thiosulfate-based coloring agent provides a non-toxic, inexpensive marking composition.

[0088] Using a carbonate mineral-based coloring agent is inexpensive and has low toxicity.

[0089] In one embodiment, the metal particles are selected from particles of bronze, gold, silver, copper, aluminum, or mixtures thereof.

[0090] Thus, the process according to the invention works with noble metals such as gold and silver or bronze-type alloys, which makes it possible to obtain high-quality and precious marked objects.

[0091] In addition, these metal particles allow the substrate to be pigmented in different colors.

[0092] In one embodiment, the marking composition comprises as coloring agent (here pigment) particles of at least one metal oxide. For example, the particles of at least one metal oxide are selected from the following transition metal oxides: - titanium oxide; - iron oxide; - tin dioxide.

[0093] These compositions allow you to obtain different marking colors.

[0094] In one embodiment, the coloring agent further comprises a particulate silicate comprised at 38% to 74% by weight in the coloring agent composition.

[0095] In one embodiment, the silicate comprises mica.

[0096] Such coloring agents, especially mica-based coloring agents, are environmentally friendly and inexpensive. In addition, mica particles improve the adhesion of the coloring agent to the substrate and absorb a part of the beam energy. Thus, the mica particles limit heating of the substrate while increasing heat transfer to the coloring agent particles, which contributes to the quality of the marking.

[0097] In one embodiment, the silicate, preferably mica, is in the form of particles having at least one of the following characteristics: - a particle size k times 10 3 greater than the size of the other particles in the coloring agent composition, with k an integer ranging from 1 to 9, - a particle size between 3.0 pm and 80 pm.

[0098] In one embodiment, the marking composition is deposited on the substrate in a layer having a thickness of between 10 nanometers and 0.1 millimeters. In one embodiment, the substrate comprises at least one of the following materials: - metal; - plastic; - a composite; - an organic material of plant origin; - an organic material of animal origin; - a material of synthetic origin, for example comprising polyurethane; - a cellulose-based material such as cardboard or paper - a woven or non-woven material at least partly of an organic nature.

[0099] For the purposes of the invention, the organic nature of a material corresponds to the fact that at least part of its components or constituents are produced by a living organism, animal or plant.

[0100] Therefore, the process works perfectly with fragile substrates such as, for example, leather goods made of natural, vegetable or synthetic leather.

[0101] In addition, the process works perfectly with harder substrates such as glass, composite, metal, plastic known for their difficulty in fixing a stable marking composition over time.

[0102] The invention also relates to a marking composition intended to be fixed on a substrate by laser irradiation comprising: - an aqueous base comprising water and a stabilizing agent, said aqueous base being present in a proportion of 50% to 84% by weight in the marking composition, - at least one coloring agent in the form of particles suspended in the base aqueous at a rate of 16% to 50% by weight in the marking composition.

[0103] A water-based base means a liquid base or a base in paste form.

[0104] The present marking composition is intended to be implemented within the framework of the method according to the invention described above.

[0105] In one embodiment, the marking composition is adapted to be fixed according to the method described above, preferably fixed on a substrate by the method described above.

[0106] Thus, the marking composition has characteristics which enable it to be fixed to fragile substrates by the method described above while exhibiting good adhesion to the substrate.

[0107] The marking composition also has characteristics that enable it to be fixed to a metal layer of a substrate by the method described below while exhibiting good adhesion to the substrate.

[0108] The adhesion of the marking composition to these different substrates is stable over time.

[0109] In one embodiment, the stabilizing agent comprises a short-chain alcohol or acrylic resin and a surfactant.

[0110] In one embodiment, the aqueous base comprises an organic solvent.

[0111] In one embodiment, each coloring agent is in the form of particles of size between 10 nm and 0.1 mm.

[0112] In one embodiment, the coloring agent is chosen from: - a pigment comprising at least one of the following elements: a metal oxide, a metal, a metal alloy, a metal alloy oxide; - an inorganic pigment; - an organic pigment; - a pigment comprising a carbonate mineral; - sodium aluminosilicate thiosulfate; - a synthetic colorant; - a natural colorant; or mixtures thereof.

[0113] In one embodiment, the coloring agent further comprises at least one silicate in particulate form, preferably mica, comprised at a rate of 38% to 74% by weight in the composition of the coloring agent.

[0114] In one embodiment, the silicate, preferably mica, is in the form of particles having at least one of the following characteristics: - a particle size k times 10 3 greater than the size of the other particles in the coloring agent composition, - a particle size between 3.0 pm and 80 pm.

[0115] In one embodiment, each coloring agent is in the form of particles with a size between 10 nm and 0.2 mm, preferably between 10 nm and 0.1 mm.

[0116] Of course, the various features, variants and embodiments of the invention may be combined with each other in various combinations to the extent that they are not incompatible or mutually exclusive.

[0117] The invention also relates to a marking composition comprising at least one coloring agent and an aqueous base. Such a composition is suitable for being fixed on a substrate by the method described above. DETAILED DESCRIPTION OF THE INVENTION

[0118] The description which follows with reference to the appended drawings, given as non-limiting examples, will make it clear what the invention consists of and how it can be implemented.

[0119] On the attached drawings:

[0120] Figure 1 is a schematic representation of one embodiment of a system for attaching a marking composition according to the present invention;

[0121] Figure 2 is an example of a deposition device included in a system for fixing a marking composition according to the invention;

[0122] Figure 3 is a first example of a fixing and / or treatment device included in a system for fixing a marking composition according to the invention;

[0123] Figure 4 is a second example of a fixing and / or treatment device included in a system for fixing a marking composition according to the invention;

[0124] Figure 5 is a first embodiment of a method of attaching a marking composition to a substrate according to the present disclosure;

[0125] Figure 6 is a front view of a planar substrate irradiated by a fixing device of a system for fixing a marking composition; and

[0126] Figure 7 is an example of a curved substrate marked with a marking composition by a fixing method according to the invention (first embodiment or second embodiment);

[0127] Figure 8 is a side view of a substrate according to the invention;

[0128] Figure 9 is a second embodiment of a method of attaching a marking composition to a substrate according to the present disclosure;

[0129] System

[0130] Figure 1 illustrates a system S for fixing a marking composition 2 on a substrate 4. The system S comprises a control unit 50 and a fixing device 10. Optionally, the system S also comprises a deposition device 20 as well as a cleaning device 60 and a synchronization device 90. In one embodiment, the system S optionally comprises a processing device 80.

[0131] As illustrated in Figure 1 and Figure 3, the fixing device 10 comprises a frame 11, a laser device 30 and a support 40. This fixing device 10 is connected to the control unit 50 which is configured to control the fixing device 10.

[0132] The control unit 50 is a computer or any other electronic element allowing a succession of commands and / or calculations to be implemented. The control unit 50 typically comprises a processor, a memory and various input and output interfaces.

[0133] Thanks to its input and output interfaces, the control unit 50 is adapted to receive input data, for example adjustment data, a pattern to be produced, the type of substrate used, etc. For this, the control unit 50 is typically connected to a human-machine interface allowing a user to enter the input data which will be used by the fixing device 10 to fix a marking composition 2 on the substrate 4.

[0134] The output data are the commands sent to the different elements of the system S.

[0135] For the fixing device 10, in particular for the laser device 30, these commands comprise, for example, adjustment data for the laser device 30 (for example, an operating mode, a power, a scanning speed, etc.). For the support 40, this data includes, for example, a distance from a focusing plane of the laser beam.

[0136] As illustrated in Figure 3, the frame 11 holds the laser device 30 as well as the support 40.

[0137] In this example, the laser device 30 comprises a laser 31 configured to irradiate the marking composition 2 positioned on the substrate 4, a scanning device 32 and a focusing device 33 comprising at least one focusing lens 34.

[0138] The laser 31 is arranged to emit a monochromatic beam 35 towards the substrate 4 in a propagation direction oriented towards the substrate 4.

[0139] In Figure 3, the laser beam 35 passes into the scanning device 32 which directs the laser beam 35 onto the substrate 4.

[0140] The scanning device 32 is configured to move the laser beam 35 on a surface 3 of the substrate 4 in two directions x, y transverse to the propagation direction of the laser beam 35. Thus, a laser scan is performed by means of the scanning device 32. Typically, the scanning device 32 consists of at least two movable mirrors for directing the laser beam 35 onto the substrate 4 so as to perform a spatial scan of the portion of substrate to be irradiated, the portion of substrate to be irradiated being defined via input data transmitted to the control unit 50. In the present disclosure, the scanning device is typically a high-speed scanning head, such as a galvo scanner. Thus, in this embodiment, the movement of the laser beam 35 is performed by means of the scanning device 32 configured to move the laser beam on the surface 3 of the substrate 4.

[0141] Typically, the scanning is carried out in a linear manner by scanning each portion of the surface of the substrate to be irradiated along a (fictitious) line defined on the substrate aligned along the x axis and then moving the laser beam 35 on another line by a movement along the y axis so as to carry out a two-dimensional (x,y) scan of the portion of substrate to be irradiated. Of course, other modes of movement can be configured such as for example a line scan along the y axis and then a movement along the x axis to carry out the two-dimensional (x,y) scan or vector scans known to those skilled in the art.

[0142] Here a scan over the portion of the substrate can be performed.

[0143] In one embodiment, the fixing device 10, in particular the laser, is configured to pass n times over each portion of the surface of the substrate 4 to be irradiated, with an integer greater than or equal to 2. Typically, n corresponds to the number of passes of the laser beam 35 over the portion of the substrate 4 to be irradiated. As specified above, in a variant n can be equal to 1 when a single pass is made.

[0144] In an exemplary embodiment, the portion of the surface of the substrate 4 has a starting point and an end point, the starting point and the end point defining the portion of the substrate 4 to be irradiated. The laser beam 35 is thus configured to pass a first time over the portion of the substrate 4 defined between the starting point and the end point. When this first pass (i.e. this first iteration) is carried out, the laser beam 35 begins to irradiate the portion of the substrate again by passing a second time over the portion of the substrate defined between the starting point and the end point. N passes can be carried out by the laser beam 35, preferably here n is equal to 3. Typically, the laser beam 35 can start at the position of the end point of the first pass and thus pass over all the points of the portion of the substrate 4 to be irradiated, ending with the starting point of the first pass. Of course, other embodiments are possible.Alternatively, on the second pass, the laser beam 35 may follow a similar path as on the first pass. In this case, the laser beam 35 starts from the starting point and ends irradiation at the end point.

[0145] The laser beam 35 is configured to pass between 2 and 40 times over each point of the portion of substrate 4 to be irradiated, preferably between 2 and 20 times, preferably between 3 and 10 (which allows for a better compromise between energy consumption and marking efficiency). Typically, the number of passes depends on the properties of the laser beam 35, for example it depends on the speed of movement and the power density of the laser beam 35. This may also depend on the type of laser 31 used, the material of the substrate which will be defined below, in particular the surface 3 of the substrate 4 which is illuminated by the laser beam 35. Etc. For example, as will be described below, for fragile substrates, such as animal leather, vegetable leather, imitation leather, the number of passes n of the laser beam is greater than or equal to 1 to fix the marking composition, for example between 5 and 10, for a power density of between 300W / mm 2 and 500 W / mm2 and a travel speed between 1500 mm / s and 2500 mm / s.

[0146] When more than two runs are programmed, it can be programmed that the even runs start from the same starting point and the odd runs start from the same starting point different from the starting point of the even runs as described above in the case of two runs.

[0147] The movement of the laser beam 35 on the surface of the substrate 4 controlled by the scanning device 32 makes it possible to create multiple patterns, shapes, symbols, designs, letters on the surface of the substrate 4. Typically, the desired patterns are previously entered into the control unit 50 which will control the scanning device 32 to produce the desired shapes.

[0148] At the output of the scanning device 32, the laser beam 35 is focused onto the substrate 4 via the focusing device 33. Here, the focusing device 33 thus has a focal distance for focusing the laser beam 35 onto a focal point included in a focusing plane.

[0149] The fixing device 10 also comprises a positioning means 12, for example one or more positioning pins, configured to define a machine reference frame. The substrate 4 has a reference frame which is locked to the machine reference frame of the fixing device 10. Thus, such positioning means make it possible to precisely move and reposition the substrate 4 in the fixing device 10. The positioning means 12 may comprise one or more positioning pins, a stand, a cradle, etc. In the example illustrated, the positioning means 12 are located on the support of the fixing device. Of course, such means may be positioned at other locations, for example on the chassis 11. The elements of the fixing device 10 are preferably locked to the machine reference frame of the fixing device 10.

[0150] The fixing device 10 optionally comprises a treatment device 80 configured to treat a metal layer of the substrate 4 by laser irradiation. Such a treatment device 80 is used if the substrate 4 has on its surface 3 a metal layer on which it is desired to fix the marking composition 2.

[0151] Typically, the metal layer requiring such treatment comprises at least one of the following materials: a metal, such as zinc or aluminum; a treated metal, such as anodized aluminum, a metalloic.

[0152] Of course, the treatment device 80 can also be used on a metal covered with a protective layer. Typically, the protective layer can comprise at least one of the following elements: an anodizing layer, a lacquer, a paint, a galvanization, a metallization, a plasticization (for example epoxy type). When the protective layer includes at least one of the following elements: a lacquer, a paint, a galvanization, a metallization, a plasticization, the metallic layer is called lacquered metal.

[0153] In one embodiment, the treatment device 80 and / or laser 30 may be removable (from the fixing device 10). Thus, in this case, the treatment device 80 and / or laser 30 are fixed to the machine reference as soon as they are inserted into the fixing device 10.

[0154] As illustrated in Figure 3, the treatment device 80 is similar to the laser device 30. This means that the treatment device 80 includes all of the elements of the laser device 30 described below and operates in a similar manner.

[0155] In a preferred embodiment, the processing device 80 and the laser device are a single element. Thus, in this preferred embodiment, the laser device 30 is configured to process the metal layer of the substrate 4 and to fix the marking composition 2 to the substrate (here the metal layer of the substrate 4). Thus, in this configuration, a single laser device 30 is used to perform two functions. Of course, in a variant of the device 10, it is possible to have two laser devices 30, one serving for the processing of the metal layer and another for the deposition of the marking composition on the metal layer.

[0156] Advantageously, the treatment device 80 is configured to pass once over an area of ​​the metal layer of the substrate 4 to be treated. This laser pass is carried out before fixing the marking composition 2 on the substrate 4. In the case of treatment by the treatment device 80, the laser device 30 is configured to fix the marking composition 2 on the treated area. This means that the laser beam 35 irradiates only the parts of the marking composition 2 positioned on the treated area of ​​the substrate 4. Typically, the treated area is included (i.e. programmed, defined) in the input data.

[0157] The substrate 4 illustrated in Figure 3 is positioned on the support 40. The support makes it possible to hold the substrate 4 in the fixing device 10. Typically, the substrate 4 can be positioned on a flat support 40. In one embodiment, the support 40 and the frame 11 are formed from a single piece. In a variant, the support 40 is not flat, it can have claws which are fixed to a part of the substrate to hold the substrate 4.

[0158] As illustrated in Figure 3, a distance d separates the surface 3 from the substrate 4 of the focusing device 33. The distance d is defined between a point of the surface 3 (here positioned in a plane PL1) of the substrate and a plane PL2 of the parallel focusing device 33. This distance d can be between 0 cm and 5 cm from the focal plane. Thus, typically, the plane PL1 can be located in the focusing plane or in a plane parallel to the focusing plane and spaced up to 5 cm from the focusing plane, the plane PL2 being parallel to the focusing plane.

[0159] In one embodiment, the support 40 is movable. In this case, the support 40 is arranged to move in at least one spatial direction. In the example illustrated in FIG. 3, the support 40 is arranged to move the substrate 4 along a z axis parallel to the propagation direction of the laser beam 35. Such an arrangement makes it possible to adjust the position of the substrate 4 relative to the focal point of the laser beam 35. In this example, the distance d is adjusted by moving the support 40. As explained above, the substrate 4 can be offset up to 5 centimeters from the focal plane (depending on the focusing device 33) or be positioned in the focal plane (including the focal point).

[0160] The position of the substrate 4 relative to the focal point of the laser beam 35 can be adjusted before the emission of the laser beam 35 or during the irradiation. Of course, in another embodiment, the support 40 can also be arranged to move the substrate 4 in three spatial dimensions x, y, z. In this case, the movement of the laser beam 35 relative to the substrate 4 can be the combination of the movement of the laser beam 35 via the scanning device 32 and the movement of the substrate 4 by a movement of the substrate 4 via the support 40.

[0161] For this purpose, the support 40 can be equipped with an electric motor (not shown) or the position of the support 40 can be adjusted via adjustment rings to position the support 40 in the correct position.

[0162] The laser 31 used in the laser device 30 is a continuous laser 31 or a pulsed laser.

[0163] Different types of lasers can be used in the system S, such as, for example, solid-state amplifying medium lasers or CO2 lasers. In the present disclosure, the solid-state amplifying medium comprises a crystal, for example, a neodymium-doped yttrium aluminum garnet crystal known as Nd-YAG or a neodymium-doped yttrium aluminum garnet crystal (Nd:YsAl2(AIO4)3).

[0164] Preferably, the laser used is arranged to emit the laser beam 35 at a power between 0.50 W and 30.0 W.

[0165] In a first embodiment, the solid amplifying medium of the laser 31 is an Nd-YAG crystal emitting a laser beam at an emission wavelength of 1064 nanometers.

[0166] In this embodiment, very good results are obtained, for example on leather, when the laser beam has a power density of 1.9 kW / mm 2 at 3.8 kW / mm 2The emitted laser beam 35 is pulsed at a pulse rate ranging from 1 kHz to 50 kHz. The power of the emitted laser beam to fix the marking composition 2 on the substrate 4 is between 7.5 and 15 Watts. In this embodiment, the laser beam 35 is configured to scan the surface of the substrate 4 at a scanning speed of between 3 m / s and 4.5 m / s. In this embodiment, the laser beam 35 typically has a laser power density of between 1.9 W / mm 2 and 3.8 kW / mm 2 in contact with the marking composition which is irradiated by the laser beam 35.

[0167] In another embodiment, laser 31 is a CO2 laser emitting an infrared laser beam at an emission wavelength of 10600 nanometers.

[0168] Preferably, the CO2 laser 31 operates in pulsed mode and emits a laser beam at a power less than or equal to 25 Watts, preferably between 3 and 25 Watts. The laser beam 35 has a pulse rate ranging from 1 kHz to 200 kHz, preferably between 1 kHz and 50 kHz. In this embodiment, very good results are obtained when the laser beam 35 has a power density of between 32 W / mm 2 and 7.7 kW / mm 2 , preferably between 60 W / mm 2 at 1.89 kW / mm 2 In this embodiment, the laser beam 35 is configured to scan the surface of the substrate 4 at a scanning speed of between 10 mm.s -1 and 9.0 m.s' 1 , preferably between 0.1 m / s to 9 m / s and has a laser power density of between 60 W / mm 2 and 5 kW / mm 2 in contact with the marking composition which is irradiated by the laser beam 35.

[0169] In another embodiment, the solid-state gain medium of laser 31 is a triple-decked Yttrium Aluminum Garnet crystal known as a Yd:YAG laser emitting a laser beam at an emission wavelength of 355 nanometers.

[0170] In this embodiment, very good results are obtained when the laser beam has a power density of between 32 W / mm 2 and 7.7 kW / mm 2 , preferably between 5.0 W / mm 2 and 60 W / mm 2 . The emitted laser beam 35 is pulsed at a pulse rate ranging from 1 kHz to 50 kHz. The power of the emitted laser beam is between 3 and 8 Watts, it is typically 5 Watts. In this embodiment, the laser beam 35 is configured to scan the surface of the substrate at a scanning speed of between 10 mm / s and 150 mm / s and typically has a laser power density of between 60 W / mm 2 and 5 kW / mm 2 in contact with the marking composition which is irradiated by the laser beam 35.

[0171] In another embodiment, the laser used is a doubled YAG laser emitting a laser beam at an emission wavelength of 532 nanometers.

[0172] In this embodiment, very good results are obtained at the fixing step when the laser beam has a power density of between 5.0 W / mm 2 and 2 kW / mm 2and a displacement speed between 10 mm / s and 2000 mm / s. Typically, for a CICP pigment (Mica + TiO2 + SnO2 + Fe2O3), very good results are obtained at a speed of 1000 mm / sec, a power density of 1.27 kW / mm 2 and for 20 laser passes. The emitted laser beam 35 is pulsed at a pulse rate ranging from 1 kHz to 50 kHz. The power of the emitted laser beam is between 3 and 8 Watts, it is typically 7 Watts.

[0173] The laser beam 35 has a diameter of between 40 and 120 micrometers, preferably between 50 and 120 micrometers in contact with the surface 3 of the substrate 4 covered with the marking composition.

[0174] The laser beam 35 of the system S thus irradiates the marking composition 2 to fix the marking composition 2 to the substrate 4.

[0175] In system S, the non-irradiated portions of the marking composition 2 are then removed by cleaning the non-irradiated portions.

[0176] In the system S, these non-irradiated parts can be cleaned manually using wipes or a sponge moistened with an aqueous composition or by the cleaning device 60 controlled by the control unit 50. The aqueous solution can comprise an alcohol or a composition of water and soap. In another variant, the non-irradiated marking composition 2 can be removed by means of an adhesive, for example with an adhesive roller.

[0177] The cleaning device 60 may comprise an ultrasonic system arranged to emit sound waves to remove parts of the marking composition 2 not irradiated by the laser beam 35. In another example, the cleaning device 60 consists of a movable arm provided with a tool, for example a moistened sponge or brush or spray device or wipe for removing the marking composition not irradiated by the laser beam 35 with an aqueous solution.

[0178] According to the present disclosure, different substrates 4 can be marked by the system S described above.

[0179] In particular, the 4-marked substrates may be fragile substrates.

[0180] Typically, fragile substrates include polyurethane, plasticized leather, artificial leather, organic substrates of animal origin such as leather (smooth, grained). Organic substrates also include pressed or dried substrates of plant origin such as cardboard, paper, imitation leathers derived from plants, called vegetable leathers or vegetable skins such as pineapple leather, mango leather, mushroom leather, tomato leather, etc.

[0181] Other types of substrates may be marked by the attachment device 10. For example, other substrates that may be marked by the attachment device 10 may include metal, plastic, glass, composite. These other substrates, referred to as hard substrates, are described in more detail using Figure 9 described below.

[0182] In the present disclosure, a substrate is said to be fragile or soft or tender, if it has a Shore A hardness of between 10 and 90, preferably between 50 and 90. The deposition properties are improved for substrates 4 having a Shore A hardness of between 50 and 90. By soft substrate, we mean a substrate configured to be mechanically marked by a low intensity action (less than 10 newtons) for example by a fingernail))

[0183] Conversely, a substrate 4 is said to be hard if it has a Shore A hardness greater than 90. These hard substrates may require surface treatment by the fixing device 10 as described above.

[0184] In some applications, the substrate may be plastic or include plastic.

[0185] Typically, in this case, the substrate may comprise at least one of the following plastics: Styrenics (ABS), Polyolefins homopolymer (PP), Polyesters (PETG), Polyamides (PA-6), Biodegradables (PLA), Recycled (PA-6 r, PS r, ABS r), Acrylics (PMMA), Polyurethane (PU) or imitation leather.

[0186] When the substrate comprises metal, the substrate may comprise at least one of the following: a metal alloy such as Brass (alloy of copper and zinc) or stainless steel (alloy of iron and carbon), a metal such as zinc or aluminum, metal with an oxide layer such as anodized aluminum), a metal comprising a protective layer such as a lacquered metal. Here, the metal may be lacquered with any of the metal layers described above. The protective layer may include: an anodizing layer, lacquering, painting, galvanizing, metallizing, plasticizing (for example epoxy type).

[0187] The substrates used can also be of different thicknesses.

[0188] Furthermore, these substrates can be of various shapes. Typically, the substrates used can be flat or curved.

[0189] The substrates according to the present disclosure may have a roughness of between 0 micrometers and 2 centimeters. The roughness depends on the substrate 4 to be marked on which the marking composition 2 is deposited.

[0190] The fragile type substrates marked by the method 100 according to the invention preferably have a Shore A hardness of between 50 and 90.

[0191] In the present disclosure, the marking composition 2 comprises: - an aqueous base at a rate of 50% to 84% by weight in the marking composition, - at least one coloring agent in the form of particles suspended in the aqueous base at a rate of 16% to 50% by weight in the marking composition. Each coloring agent of the marking composition 2 is in the form of particles with a size between 10 nm and 0.1 mm.

[0192] The aqueous base serves as the application vector for the marking composition 2.

[0193] The aqueous base includes water and a stabilizing agent.

[0194] Typically, the stabilizing agent comprises a short-chain water-soluble alcohol or mixed acrylic resin and a surfactant.

[0195] When using alcohol, such an aqueous base helps to reduce the surface tension "coloring agent / water - substrate". The alcohol's role is in particular to accelerate the drying of the marking composition on the surface of the substrate.

[0196] In one embodiment, the aqueous base may comprise a water-missible organic solvent. Typically, the organic solvent is selected from acetaldehyde, acetic acid, acetone, acetonitrile, dimethoxyethane, dimethylformamide, dimethyl sulfoxide (DMSO), dioxane, ethanol, ethylamine, ethylene glycol, glycerol, methanol, propanol, propylene glycol, tetrahydrofuran, triethylene glycol. Of course, other organic solvents can be used.

[0197] In a preferred embodiment, the aqueous base, in particular the stabilizing agent, does not comprise an organic solvent.

[0198] For example, when the stabilizing agent is a water-soluble short-chain alcohol, the short-chain alcohol may comprise a C2-C3 base or may be methanol.

[0199] When the stabilizing agent is an acrylic resin and a surfactant, the acrylic resin mixed with water intervenes in the process of fixing the coloring agents.

[0200] In this case, the surfactant can be selected from anionic surfactants, cationic surfactants, non-ionic surfactants such as esters, zwitterionic surfactants, polymeric surfactants, bio-sourced surfactants belonging to one of the preceding categories.

[0201] The surfactant used depends on the coloring agent that will be used in the marking composition.

[0202] The coloring agent may be chosen from: - a pigment comprising at least one of the following elements: a metal oxide, a metal, a metal alloy, a metal alloy oxide; - an inorganic pigment; - an organic pigment; - a carbonated mineral pigment; - sodium aluminosilicate thiosulfate; - a synthetic colorant; - a natural colorant; or may be mixtures of the coloring agents listed above.

[0203] Typically, when the coloring agent comprises a pigment, the pigment may be in particulate form.

[0204] For example, when the coloring agent (here the pigment of the coloring agent) comprises particles of at least one metal, these particles are selected from Bronze, Gold, Silver.

[0205] As described above, the coloring agent may be a mixture of several distinct pigment particles.

[0206] For this purpose, in one embodiment, the coloring agent further comprises at least one silicate, preferably mica, included at a rate of 38% to 74% by weight in the composition of the coloring agent.

[0207] Typically, when the silicate comprises mica or is mica, the mica particles may be coated with particles of one or more metal oxides.

[0208] The particles of at least one metal oxide are selected from the following transition metal oxides: - titanium oxide; - iron oxide; - tin dioxide.

[0209] In one embodiment, the coloring agent or marking composition has photochromic properties and / or thermochromic properties.

[0210] The detailed examples below describe different coloring agents of the marking composition 2 used in the method 100 which will be described below. In particular in these examples, the coloring agent comprises at least one pigment in the form of particles.

[0211] Example 1

[0212] In this example, the coloring agent comprises a pigment in the form of particles. The particles are bronze particles made from an alloy of copper and tin known to those skilled in the art. The bronze particles have a particle size of between 10 nanometers and 20 μm. The bronze particles are mixed in the aqueous base comprising water and a short-chain alcohol but remain insoluble. For example, the bronze particles are present at 16.6% by weight in the marking composition 2, the isopropanol of the aqueous base is present at 16.6% by weight in the marking composition 2 and the water of the aqueous base is present at 66.6% by weight in the marking composition 2. This composition is then applied to the substrate manually or via the deposition device 20. The color obtained by this marking composition is typically the color GOLD.

[0213] Example 2

[0214] In this example, the coloring agent comprises a pigment comprising carbon particles and iron oxide (Fe2O3) particles. The carbon particles have a particle size between 10 nanometers and 100 pm. Such a coloring agent produces a black color. The iron oxide particles are mixed in the aqueous base comprising water and a short-chain alcohol but remain insoluble. For example, the coloring agent is present at 16.6% by weight in the marking composition 2, the isopropanol of the aqueous base is present at 16.6% by weight in the marking composition 2 and the water of the aqueous base is present at 66.6% by weight in the marking composition 2. This composition is then applied to the substrate manually or via the deposition device 20.

[0215] Example 3

[0216] In this example, the coloring agent comprises a pigment comprising particles of synthetic or natural mica associated (here coated) with particles of a noble metal selected from Gold to obtain a gold / golden color or Silver to obtain a silver color.

[0217] In this embodiment, the mica particles are a thousand times larger than the silver or gold particles. Typically, the mica particles have a size of the order of a micrometer while the gold or silver particles have a size of the order of tens / hundreds of nanometers. The mica particles are present at a rate of 80 to 99% by weight in the composition of the coloring agent. These particles are mixed with the aqueous base as described above.

[0218] For example, the coloring agent is present at 16.6% by weight in the marking composition 2, the isopropanol of the aqueous base is present at 16.6% by weight in the marking composition 2 and the water of the aqueous base is present at 66.6% by weight in the marking composition 2. This composition is then applied to the substrate manually or via the deposition device 20.

[0219] Example 4

[0220] In this example, the aqueous base comprises an acrylic binder and a surfactant. Typically, in this embodiment, the coloring agent is 30% by weight in the marking composition 2, the acrylic binder is 64% by weight in the marking composition 2 and the surfactant is 66.6% by weight in the marking composition 2. The surfactant may comprise Sodium lauryl sulfoacetate.

[0221] The coloring agent comprises a pigment comprising synthetic or natural mica particles mixed with metal oxide particles.

[0222] Mica particles are present at a rate of 38 to 74% by weight in the coloring agent composition. The remainder of the coloring agent composition being composed of particles of at least one metal oxide. In this example, the mica particles have a size between 3.8 pm and 74 pm.

[0223] Different compositions of the coloring agent can be considered.

[0224] Case 1: The coloring agent of the marking composition comprises mica particles, titanium dioxide (TiC) particles, tin dioxide (SnC) particles and iron oxide (Fe2O3) particles each having a particle size of between 10 micrometers and 60 micrometers. For example, the mica particles are present at 66% to 74% by weight in the coloring agent composition, the TiC particles are present at 15% to 19% by weight in the coloring agent composition, the Fe2O3 particles are present at 11% to 15% by weight in the coloring agent composition and the SnO2 particles are present at less than 1% by weight in the coloring agent composition. This coloring agent is mixed with the aqueous base as described above to obtain marking composition 2. According to this example, marking composition 2 irradiated on the substrate is gold / golden in color.

[0225] Case 2: The coloring agent of the marking composition comprises in this example, mica particles, titanium dioxide (TiC) particles and iron oxide (Fe2O3) particles each having a particle size between 10 micrometers and 60 micrometers. This coloring agent is mixed with the aqueous base as described above to obtain marking composition 2. According to this example, marking composition 2 irradiated on the substrate is gold / golden in color.

[0226] Case 3: The coloring agent of the marking composition comprises in this example mica particles, iron oxide (Fe2O3) particles having a particle size between 5 micrometers and 23 micrometers. This coloring agent is mixed with the aqueous base as described above to obtain marking composition 2. According to this example, marking composition 2 irradiated on the substrate is gold / golden in color.

[0227] Case 4: The coloring agent of the marking composition comprises in this example mica particles, titanium dioxide (TiC) particles having a particle size between 10 micrometers and 60 micrometers. This coloring agent is mixed in the aqueous base as described above to obtain the marking composition 2. According to this example, the marking composition 2 irradiated on the substrate is white in color.

[0228] Case 5: The coloring agent of the marking composition comprises mica particles and iron III oxide (Fe2O3) particles. This coloring agent is mixed with the aqueous base as described above to obtain marking composition 2. According to this example, marking composition 2 irradiated on the substrate is green in color.

[0229] Case 6: The coloring agent of the marking composition comprises mica particles present at 69% to 73% by weight in the coloring agent composition and titanium dioxide particles at 26% to 30% by weight in the coloring agent composition. This coloring agent is mixed with the aqueous base as described above to obtain marking composition 2. According to this example, marking composition 2 irradiated on the substrate is gray in color.

[0230] Case 7: The coloring agent of the marking composition comprises mica particles, iron oxide particles and tin dioxide (SnC) particles. This coloring agent is mixed with the aqueous base as described above to obtain marking composition 2. According to this example, marking composition 2 irradiated on the substrate is yellow in color.

[0231] Case 8: The coloring agent of the marking composition comprises mica particles, iron oxide particles and titanium dioxide (TiC) particles. This coloring agent is mixed with the aqueous base as described above to obtain marking composition 2. According to this example, marking composition 2 irradiated on the substrate is orange in color.

[0232] Case 9: The coloring agent of the marking composition comprises mica particles, SnO2 particles, and TiC particles. This coloring agent is mixed with the aqueous base as described above to obtain marking composition 2. According to this example, marking composition 2 irradiated on the substrate is purple in color.

[0233] Case 10: The coloring agent of the marking composition comprises mica particles, TiC particles and Fe2O3 particles. This coloring agent is mixed with the aqueous base as described above to obtain the marking composition 2. According to this example, the marking composition 2 irradiated on the substrate is black in color.

[0234] Case 11: The coloring agent of the marking composition comprises mica particles, and Fe2O3 particles. This coloring agent is mixed with the aqueous base as described above to obtain marking composition 2. According to this example, marking composition 2 irradiated on the substrate is red in color.

[0235] Although the coloring agents of this example are shown mixed with an aqueous composition comprising an acrylic binder and a surfactant, in an alternative embodiment, the coloring agent may be mixed in an aqueous base comprising a short-chain alcohol as shown in the previous examples.

[0236] Example 5

[0237] In one embodiment, the coloring agent comprises a pigment comprising at least one of the following particles: - ceramic enamel particles composed of silica, - fondant particles, - alumina particles, or mixtures thereof.

[0238] Such a coloring agent is a gray color. Typically, the coloring agent is 16.6% by weight in the marking composition 2, the isopropanol of the aqueous base is 16.6% by weight in the marking composition 2, and the water of the aqueous base is present at 66.6% by weight in the marking composition 2.

[0239] Example 6

[0240] In this example, the coloring agent comprises a pigment comprising aluminum oxide particles coated with titanium dioxide and also comprises tin oxide. The particles of the coloring agent are in this example between 5 μm and 60 μm, here from 5 μm to 30 μm. Such a coloring agent makes it possible to obtain a blue color. The aluminum oxide particles are mixed in the aqueous base comprising an acrylic binder and a surfactant. For example, the coloring agent is present at 30% by weight in the marking composition 2, the aqueous base is present at 66% by weight of the marking composition. In this example, the aqueous base comprises an acrylic binder at 60% by weight in the marking composition 2 and the surfactant is present at 6% by weight in the marking composition 2. This composition is then applied to the substrate manually or via the deposition device 20.

[0241] In order to carry out the marking according to the invention, the marking composition 2 must be deposited on a surface 3 of the substrate which will be positioned facing the beam. laser 35, this deposit can be carried out in various ways.

[0242] In the present disclosure, the marking composition 2 may be deposited manually on the substrate 4, for example using a brush. In this case, the deposited marking composition 2 may have a thickness of less than 1 mm, preferably between 0.01 mm and 0.1 mm.

[0243] In one variant, the marking composition can be deposited automatically via the deposition device 20. For this purpose, the deposition device 20 is controlled by the control unit 50.

[0244] Typically, the deposition device 20 may comprise a movable arm provided with a tool, for example a brush arranged to deposit the marking composition on the surface 3 of the substrate 4. The deposition of the marking composition 2 is preferably carried out in a linear manner on the substrate 4.

[0245] In a variant illustrated in Figure 2, the deposition device 20 uses an application rod according to a technique known under the English name of Rod Coater. As illustrated in Figure 2, the deposition device 20 comprises in this example a movable cylindrical rod 21 covered with a wire 22 wound around the rod 21 so as to form a coil. In Figure 2, the substrate 4 is positioned on the support 40. A portion of the marking composition 2 is deposited on the surface 3 of the substrate 4 at a given position P, for example by spraying. A rotation (movement) of the rod 21 in a direction 6 allows the deposition of the marking composition 2 on the substrate 4 in the direction 6.

[0246] The thickness of the marking composition 2 depends on the thickness of the wire 22 used. The speed of movement of the rod 21 is controlled by the control unit 50. It typically varies between 2 and 15 m / min.

[0247] In the present disclosure, the deposition device 20 is configured so that the marking composition 2 has a thickness of between 10 μm and 20 mm, for example of between 10 μm and 100 μm.

[0248] Figure 4 illustrates a second example in a fixing device 70. Only the differences with Figure 3 will be described.

[0249] In this example, the fixing device 70 comprises a frame 11, a laser device 30 comprising a laser 31 emitting a laser beam 35, a focusing device 33 comprising the focusing lens 34 as well as a support 40.

[0250] In this example, the fixing device 70 does not include a scanning device.

[0251] Here, the support 40 is a movable support 40 arranged to move in three spatial directions x, y, z as explained in the previous example. Therefore, in this embodiment, the movement of the laser 35 is achieved by means of the movement of the substrate 4.

[0252] First, the distance between the substrate 4 and the focusing device 33 is adjusted by moving the support 40 along the z axis so as to position the substrate at the desired distance from the focusing point of the focusing device. This distance can be adjusted before the emission of the laser beam 35 or adjusted during the irradiation of the laser.

[0253] Then, the laser beam 35 at the output of the focusing device 33 moves on the substrate 4 via the movable support 40 which will move in the two spatial directions x, y. Typically the movement of the support 40 is linear. The support 40 moves on a (fictitious) line along the x axis then passes to another line by a movement along the y axis so as to obtain a relative movement of the laser beam 35 with respect to the substrate 4. By the movement in two dimensions (x, y) of the support 40, the laser beam 35 irradiates the portion of substrate to be irradiated to obtain the desired pattern.

[0254] For this purpose, the fixing device 70 may comprise a synchronization device 90 for synchronizing the movement of the substrate 4 relative to the laser beam 35. In this case, the synchronization device 90 is controlled by the control unit 50.

[0255] Process

[0256] A first example of a method 100 for fixing a marking composition to a substrate will be written using figures 5 to 8. The marking composition 2 used is that described above, which is a marking composition suitable for being fixed to a substrate by the method 100 (or 200 as will be explained below).

[0257] The method illustrated in Figure 5 is implemented by the system S illustrated in Figure 1.

[0258] The method 100 comprises a step 102 of depositing the marking composition 2 on at least a portion of the substrate 4. In this example, the substrate 4 is grained polyurethane having an average particle size of 35 μm.

[0259] As explained above, this deposition on the substrate 4 can be carried out manually, for example using a brush, or automatically by via the deposition device 20 as explained above. If the deposition of the marking composition 2 is carried out outside the fixing device 10, 70, the substrate 4 is wedged on the machine reference frame of the fixing device 10, 70, for example using the positioning means 12 of the fixing device 10, 70.

[0260] When the marking composition 2 is deposited on the substrate, here in particular, on the surface 3 of the substrate, the method 100 optionally comprises a step 103 of drying the marking composition 2.

[0261] The drying step 103 depends on the marking composition 2 used.

[0262] Typically, the drying step 103 is carried out in the open air. The drying time depends on the marking composition 2 and the material of the substrate 4. In the example presented, the drying time is less than two minutes.

[0263] The method 100 then comprises a step 104 of fixing a portion of the marking composition 2 by laser irradiation. The fixing step 104 is carried out by the fixing device 10 illustrated in FIG. 3 or the fixing device 70 illustrated in FIG. 4, in particular by the laser device 30 of the fixing device 10, 70 which will emit the laser beam 35. As illustrated in FIG. 5, the laser beam 35 irradiates the substrate 4 at a point or spot 36. Here, the laser beam 35 has a diameter at the surface 3 of the substrate 4 of 90 μm. The laser beam 35 is then moved over the surface 3 of the substrate 4 to obtain a desired pattern on the surface 3 of the substrate 4.

[0264] As explained above, the movement of the laser beam 35 can be carried out using the scanning device 32 as illustrated in FIG. 3 or by a movement of the substrate 4 by means of a movable support 40 or by a combination of the two aforementioned movements. The scanning device 32 and / or the movement of the substrate 4 along the x, y axes makes it possible to orient the laser beam 35 at the desired positions on the surface 3 of the substrate 4.

[0265] Here, typically, during the fixing step 104, the laser beam 35 has a power density of between 32 W / mm 2 and 7.7 kW / mm 2 , preferably between 60 W / mm 2 and 5 kW / mm 2 , in contact with the irradiated marking composition 2 and the displacement of the laser beam is carried out at a speed, measured relative to the substrate, between 10 mm. s -1 and 9.0 m.s' 1 , preferably between 0.10 ms -1and 9.0 m.s' 1 .

[0266] In one embodiment, the color of the coloring agent remains the same (before and after laser fixation). However, in a variant, the coloring agent may comprise thermochromic pigments that can change color upon laser irradiation.

[0267] The method 100 optionally comprises a step 106 of removing the marking composition which has not been irradiated in the fixing step 104.

[0268] Typically, the removal step 106 may be performed manually or via the cleaning device 60 as described above.

[0269] The removal step 106 makes it possible to remove the parts of the marking composition 2 which were not irradiated by the laser beam 35 in the fixing step 104.

[0270] It can be seen that the substrate 4 illustrated in FIG. 5 obtained following the removal step 106 is marked by a gold-colored marking. In this example, nine gold patterns 16 of 3 millimeters by 3 millimeters have been marked on the substrate 4. Apart from the patterns 16, the substrate 4 has portions 17 which have not been marked. This means that these portions 17 have not been irradiated by the laser beam 35 during the fixing step 104.

[0271] The marking composition 2 irradiated by the laser beam 35 did not change color (pigmentation) between the deposition step 102 and the fixing step 104.

[0272] Figure 7 illustrates an example of a substrate 4 obtained following the application of the method 100 to the substrate 4.

[0273] The substrate 4 illustrated in figure 6 is a grained leather having an average roughness of 35 μm and has two parts, a first part 14 which has not been covered with marking composition and a second part 15 which has been covered with marking composition 2 in the deposition step 102. In this example, the first part 14 of the substrate 4 and the second part 15 of the substrate 4 were irradiated in the fixing step 104 by a CO2 laser beam as described above (the irradiations on the first and second parts were carried out with the same laser parameters).

[0274] Here, the laser beam 35 irradiated the portions P1, P2, P3 and P4 of the first part 14 and the portions P5, P6, P7 and P8 of the second part 15 of the substrate 4.

[0275] As illustrated in Figure 6, the substrate 4 has no marks on the portions P1, P2, P3 and P4 while on the portions P5, P6, P7 and P8, 18 square patterns of 5 mm by 5 mm of gold color have been marked on the surface 3 of the substrate 4. In the second part 15, all the portions P5, P6, P7 and P8 of the substrate 4 are covered by the marking composition 2, this marking composition 2 being fixed to the substrate 4. Thus, the laser beam 35 has not marked or damaged the first part 14 of substrate 4 which has nevertheless been irradiated.

[0276] Typically, the marking composition 2 in the portions P5, P6, P7 and P8 covers at least ninety percent of the irradiated portions P5, P6, P7 and P8 of the substrate 4.

[0277] By coverage rate, we mean the ratio between the effective marked surface (i.e. pigmented or colored, here the surface of the marking composition fixed on the substrate 4) following the method 100 on the effective irradiated surface. In this example, each portion P5, P6, P7 and P8 corresponds to an effective irradiated surface in the second part 15 of the substrate 4. Here for each portion P5, P6, P7 and P8, the effective marked surface is obtained by comparing the effective irradiated surface (here the surface of the portions P5, P6, P7 and P8) to the shares of the non-irradiated substrate in each portion P5, P6, P7 and P8.

[0278] Figure 7 illustrates an example of a bottle or flask B made of synthetic leather or artificial leather (polyurethane) having a cylindrical shape. As illustrated in Figure 7, a golden pattern M is marked on the surface 3 of the substrate 4 of the box B. This pattern M was marked by using the method 100 described above.

[0279] Typically, in the method 100, the box M has been positioned with respect to the focusing device 33 before the fixing step 104, here following or during the drying step 103.

[0280] The distance d separating the surface of the substrate 4 from the box B and the focusing device 33 was adapted to the shape of the box B. Since the method 100 can mark substrates positioned up to 5 cm from the focusing plane, it was not necessary to adapt the distance d during the fixing step 104 even though the substrate is curved. Indeed, these 5 cm make it possible to encompass the shapes and curvatures of the substrate to be marked during the fixing step.

[0281] The method 100 is typically used when the substrate, in particular the surface 3 of the substrate 4 which is in contact with the laser beam 35 in the fixing step, comprises at least one of the following elements: - an organic material of plant origin; - an organic material of animal origin; - a synthetic material; - a cellulosic material; - a metallic material; - a plastic material; - a composite material; - a mixture or assembly of several of the preceding materials.

[0282] Animal organic materials include, for example, leathers (e.g., mammalian leather such as cattle, vertebrate leather such as fish or snake leather, etc.). Plant organic materials include the various types of plant leathers (e.g., mango skin, pineapple skin, mushroom or mushroom mycelium, etc.).

[0283] Plastic materials also include synthetic leathers, such as imitation leather.

[0284] Examples of implementation of the method 100 on different substrates will now be described.

[0285] The results obtained presented below were obtained with flat substrates having an average roughness of less than 2 cm, preferably 50 mm, preferably less than 1 mm. The coloring agents presented are used in the marking composition as described above, i.e. comprising an aqueous base (water + a short-chain alcohol or an acrylic binder mixed with a surfactant) at a rate of 50% to 84% by weight in the marking composition and at least one coloring agent (as described below) at a rate of 16% to 50% by weight in the marking composition.

[0286] For example, Table 1 illustrates examples of implementation of the method 100 on a substrate having a surface 3 comprising a fragile material as described above (leather, imitation leather, vegetable skin).

[0287] The coloring agents used include at least one of the elements presented above.

[0288] [Table 1] above (device) and were obtained with a single pass (n equal to 1) of the laser beam at the fixing step 104 or several passes (n greater than or equal to 2).

[0290] For these results, the laser beam used has a power density of between 32 W / mm 2 and 7.7 kW / mm 2 and a movement speed between 10 mm / sec and 9 m / sec.

[0291] Preferably, better brand results while limiting substrate damage are achieved with a power density of 300W / mm 2 and 500 W / mm 2 , a movement speed between 1500 and 2500 mm / sec and for a number of passages greater than 1, preferably between 3 and 10, preferably between 5 and 10.

[0292] Table 2 illustrates examples of implementation of the method 100 on a substrate having a surface comprising a (non-fragile) plastic material, said plastic material being irradiated in the fixing step.

[0293] The results obtained presented below were obtained with flat substrates having an average roughness of less than 2.00 cm, preferably less than 0.50 cm, preferably less than 1.00 mm.

[0294] The plastic materials (polymer) suitable for being marked by the method 100 include at least one of the following plastics: styrenics (ABS), homopolymer polyolefins (PP), polyesters (PETG), polyamides (PA-6), biodegradables (PLA), recycled (PA-6 r, PS r, ABS r), acrylics (PMMA).

[0295] For example, Table 1 illustrates examples of implementation of the method 100 on a substrate having a surface comprising a plastic material marked by the method 100.

[0296] [Table 2]

[0297] The solid-state amplifying medium lasers used described in this Table 2 are similar to those described above (device) and were obtained with a single pass or multiple passes of the laser beam at the fixation step 104.

[0298] For these results, the laser beam used has a power density of between 32 W / mm 2 and 7.7 kW / mm 2 and a movement speed between 10 mm / s and 9 m / sec, for example for at least one pass of the laser beam.

[0299] Metallic materials suitable for marking by the 100 process comprise metal covered by a protective layer, such as for example an anodizing layer (example for anodized aluminum) or a layer of lacquer or the like and called lacquered metal as described above. Different coloring agents can be used in the marking composition used in the method 100 for marking (marking surface 43) an anodized metal or a lacquered metal. These coloring agents comprise one of the following: organic pigments, white inorganic pigment, colored CICP inorganic pigment, colored synthetic pigment made of metal oxides, colored natural inorganic pigment, synthetic dyes and ingrain dyes, coloring agent based on natural dyes, as described in Table 1 and Table 2. In this case, the laser used in the fixing step is preferably a CO2 laser emitting at 10600 nm and having a power density and used at a speed similar to that described above (case Table 2).

[0300] It is thus understood that the substrate presented above may have other materials, for example other layers of materials which will not be treated by the method 100 (i.e. no step of the method 100 implemented on these layers).

[0301] A second example of a method 200 according to the present disclosure will now be described with the aid of FIG. 8 and FIG. 9. The method 200 illustrated in FIG. 9 is implemented by the system S illustrated in FIG. 1. Only the differences with the method 100 described with the aid of FIG. 5, FIG. 6 and FIG. 7 will be described.

[0302] Figure 8 illustrates a side view of a substrate 42 adapted to be marked according to the method 200. Of course, as described above, the substrate illustrated in Figure 8 can also be, in the examples explained above, marked by the method 100.

[0303] The substrate 42 may be of any type. Typically, the substrate 42 used in the method 200 comprises at least one of the following materials: - metal; - plastic; - glass; - ceramics; - stone; - brick; - a composite; - an organic material of plant origin; - an organic material of animal origin; - a synthetic material; - a cellulosic material, or a mixture or assembly of several layers of these previous materials.

[0304] Thus, the substrate 42 may comprise a brittle material, such as one listed in the method 100, or a material having a higher hardness coefficient (i.e., a Shore A hardness coefficient greater than or equal to 80.

[0305] The substrate 42 has a surface 43 which comprises, in this embodiment, a metal layer 44. The surface 43 is also called the marking surface 43.

[0306] For example, the metal layer 44 comprises a layer of at least one of the following materials: - a metal; - a metal alloy; or a mixture or assembly of several layers of these previous materials.

[0307] The substrate 42 may comprise another layer 41 made of another material. In the example illustrated in FIG. 9, the substrate 42 is made of a single material, here a single 5 mm thick layer of anodized aluminum.

[0308] The substrate 42 illustrated in FIG. 8 is positioned in the fixing device 10 illustrated in FIG. 3 or the fixing device 70 illustrated in FIG. 4 to be marked by the marking composition 2 via the steps of the method 200 which will be described below. For this purpose, the substrate 42 is positioned relative to the machine reference frame of the fixing device 10, 70.

[0309] Unlike the method 100 illustrated in FIG. 5, the method 200 comprises, before the deposition step 102, a step 202 of treatment of the metal layer 44 by laser irradiation.

[0310] Here, typically, the processing step 202 is performed by the processing device 80 illustrated in FIG. 3 and FIG. 4.

[0311] In order to promote compactness and costs, the processing device 80 is similar to the fixing device 30 described above. Typically, the processing step 202 is carried out by the laser device 30 which will emit a laser beam onto the metal layer 44 of the substrate 42. As illustrated in FIG. 9, the laser beam can irradiate or illuminate the surface of the metal layer 44 along a diameter 90 pm beam.

[0312] In the processing step 202, the laser beam may move over the surface of the metal layer 44 by laser scanning, typically using the galvo head 32 as illustrated in FIG. 3 or by moving the substrate 4 as illustrated in FIG. 4. The movement of the laser beam locally causes a surface treatment of the metal layer 44, in particular a chemical transformation of the surface of the metal layer 44 or a physical transformation of the metal layer depending on the substrate. The area scanned by the laser beam 35 thus forms a treated area 45 on the metal layer 44.

[0313] In the treatment step 202, one pass of the laser beam over the metal layer 44 makes it possible to obtain the treated area 45. Of course, in a method variant 200, the laser beam can make several passes over the metal layer 44. However, these additional passes cause additional energy consumption.

[0314] In this example, during the processing step 202, the laser beam moves on the surface of the metal layer 44 to form a desired shape pattern. This desired shape is for example programmed in the input data or defined by default by the system S. The default shape can be a rectangular or square or circular or oval shape. As illustrated in FIG. 9, the treated area 45 is broken down into a circular shape pattern with a diameter of 5 mm. Of course, other shapes can be obtained depending on the movement of the laser during the processing step 202 as described above. Typically, the treated area 45 can have a shape relating to one or more personalized patterns (for example a logo, a name, a succession of words, a succession of letters, an image, etc.). Thus, the treated area 45 can be broken down into different disjointed parts on the surface 43 of the metal layer 44.

[0315] For example, if a CO2 laser emitting at 10600 nm, then the power density can be between 955 W / mm 2 and 1.27 kW / mm 2 and the speed can be between 500 mm / sec and 900 mm / sec.

[0316] For example, if a YAG laser emitting at 355 nm, then the power density can be between 1 kW / mm 2 and 1.9 kW / mm 2 (preferably 1.7 kW / mm 2 ) and the speed can be between 1000 mm / s and 1600 mm / s (preferably 1500 mm / s).

[0317] In this example, the treated area 45 of the metal layer 44 (here the pattern circular) has a surface color that distinguishes it from the areas not treated by the laser beam (i.e., the areas of the metal layer 44 that have not been illuminated by the laser beam). The treated area 45 advantageously has a white color or a grayscale color. The color of the treated area 45 depends in particular on the properties of the laser beam, such as the speed of movement of the laser beam and / or the power density of the laser beam. It may also depend on the material of the metal layer 44. Thus, in the method 200, it is possible to select the grayscale of the treated area 45 by adjusting the laser illumination parameters, for example by adjusting the number of passes, and / or the power density and / or the speed of movement.

[0318] Typically, with method 200, when the metal layer 44 (especially the marking surface) is made of anodized aluminum, the processing step can use a power density of between 955 W / mm 2 and 1.27 kW / mm 2 and a laser beam movement speed of between 500 mm / sec and 900 mm / sec, in the case, for example, of using a CO2 laser. Such parameters make it possible to obtain better results in fixing the marking composition while limiting the energy consumption of the process 200.

[0319] In the method 200, the color of the treated area 45 can affect the fixing performance of the marking composition 2. For example, for anodized aluminum, it is preferable for the treated area 45 to remain gray in color in order to facilitate adhesion of the marking composition during a fixing step 206 is facilitated and is stable over time. In addition, the better the final rendering of the color of the coloring agent of the marking composition on the metal layer 44.

[0320] At the end of the treatment step 202, a treated area 45 on the surface of the metal layer 44 is obtained.

[0321] The method 200 then comprises a step 204 of depositing the marking composition 2 which is, in this example, similar to the step 102 of depositing the method 100. Here, in particular, the depositing of the marking composition 2 is carried out by the depositing device 20 illustrated in FIG. 2 or carried out manually, for example using a brush. As explained above, if the depositing requires moving the substrate and repositioning it in the same position, then in the method 200, the substrate 4 is wedged in the same machine reference frame of the fixing device 10, 70 by means of the positioning means 12.

[0322] In the deposition step 204, the deposition device 20 deposits a layer of the marking composition 2 on the treated area 45 of the metal layer 44. The marking composition can also cover untreated areas of the metal layer 44. If, during deposition, the substrate 42 is moved, the substrate is then repositioned in the fixing device 10, 70, aligned with the machine reference frame of the fixing device 10, 70.

[0323] In the method 200 illustrated in Figure 9, the marking composition 2 comprises an aqueous base and at least one coloring agent as described previously. The aqueous base may therefore comprise water with a short-chain alcohol or an acrylic binder mixed with a surfactant.

[0324] Advantageously, the coloring agent (in the form of particles) of the marking composition 2 is adapted to be fixed on the treated area 45. Such a coloring agent comprises silicate particles covered by metal oxide particles or silicate particles covered by particles of at least one noble metal. The silicate particles are selected from mica. When the silicate particles comprise mica or are mica, the coloring agent used in the marking composition may be the coloring agent described in Example 3 described above which has a coloring agent composed of mica particles covered by particles of at least one noble metal or the coloring agent of Example 4 described above which has a coloring agent composed of mica particles covered by particles of at least one metal oxide.

[0325] In another embodiment, the coloring agent comprises particles of at least one metal alloy or metal particles of at least one transition metal. Thus, the coloring agent may be similar to that of Example 1 described above, or to that of Example 5 described above or to that of Example 6 described above.

[0326] In another variant, the coloring agent comprises particles of at least one carbonate mineral. Thus, the coloring agent may be similar to that of Example 2 described above.

[0327] In another variant, the coloring agent comprises sodium aluminosilicate thiosulfate particles.

[0328] In another embodiment, the coloring agent comprises a pigment comprising particles of at least one inorganic material as described above, for example particles of Cu2(COs)(OH)2) or Mica- TiC - SnO2 - Fe2O3 (table 1 or table 2).

[0329] In another variant, the coloring agent comprises pigment comprising particles of at least one organic material. The organic materials may comprise a polyoxymethylene melamine-based material.

[0330] In a variant, the coloring agent or the marking composition has photochromic properties and / or thermochromic properties which are not altered by the steps of the method 200, in particular during the step 206 of fixing the coloring agent or during the step 208 of removing it.

[0331] Where the coloring agent comprises photochromic properties, such coloring agent may be similar to the coloring agent described in Example 7 set forth below.

[0332] Example 7

[0333] In this example 7, the coloring agent is a coloring agent composition comprising: - between 21.0% and 24.0% of Polyoxymethylenemalamine particles; - between 1.3% and 1.8% of blue photochromic pigment; - monomethyl styrene maleic anhydride particles comprising: * between 62.0% and 68.0% mineral oil; * between 7.5% and 9.5% maleate polymer;

[0334] Where the coloring agent comprises thermochromic properties, such coloring agent may be similar to the coloring agent described in Example 8 set forth below.

[0335] Example 8

[0336] In this example 8, the coloring agent is a coloring agent composition comprising: - between 19.0% and 27.2% of polyoxymethylene melamine particles (known under the English name of “polyoxymethylene melamine”); - between 5.8% and 7.2% of styrene maleic anhydride monomethyl maleate polymer particles (known in English as “styrene maleic anhydride monomethyl maleate polymer”; - between 2.0% and 4.2% of ODB-II particles (2'-Anilino-6'-(dibutylamino)-3'-methyl- 3H-spiro[2-benzofuran-1,9'-xanthen]-3-one); - between 0.3% and 0.7% of black DCF particles (known as “Black DCF”); - between 45.6% and 47.5% of ethyl stearate particles (known as “ethyl stearate”); - between 15.2% and 15.8% of methyl palmitate particles (known as “methyl palmitate”).

[0337] Following the deposition step 204, the method 200 optionally comprises a drying step 205. The drying step 205 is identical to the drying step 103 described in the method 100.

[0338] The method 200 comprises a step 206 of fixing the marking composition 2 by moving the laser beam 35 over the surface of the substrate covered with the marking composition 2. In this example, the fixing step 206 of the method 200 is identical to the fixing step 104 of the method 100. Thus, in the fixing step 206, the laser device 30 emits the laser beam 35 which will move along the surface of the metal layer 44 covered by the marking composition 2. Thus, in this step 206, the marking composition 2 is fixed to the treated area 45 of the metal layer 44 by illuminating or irradiating this treated area 45 with the laser beam 35. As specified above, the surface of the substrate irradiated by the laser beam 25 can be positioned at the focal point or be offset from the focal point (preferably up to 5 cm).

[0339] Advantageously, in the method 200, the laser beam 35 is programmed to move only over the treated area 45 of the substrate 42 in order to fix the marking composition at the treated area(s). Thus, in the fixing step 206, the laser beam 35 follows a movement which is similar to the movement of the laser beam in the treatment step 202. Therefore, in the illustrated example, the laser beam 35 emitted in the fixing step 206 irradiates only the treated area 45.

[0340] Preferably, in the fixing step 206, the laser beam 35 irradiates the treated area 45 by making a first pass over the entire treated area 45, i.e. by irradiating the entire surface of the treated area 45. In this first pass, the laser beam 35 has, as in the method 100, a power density of between 60 W / mm 2 and 5 kW / mm 2in contact with the marking composition 2 covering the treated area 45 and a movement carried out at a speed, measured relative to the substrate 42, at a speed of between 0.1 m.s' 1 and 0.9 m.s' 1 .

[0341] After having carried out this first pass, the laser beam 35 irradiates at least a second time the treated area 45 by passing once again over the entire treated area 45. In this second pass, the laser beam 35 can follow a movement similar to the first pass, that is to say start from the same starting point and end with the same arrival point or start from the arrival point of the previous pass to return to the starting point of the previous pass, or follow another movement while passing only over the parts of the marking composition 2 which were irradiated in the first pass of the laser beam 35. In addition, the irradiation parameters, here the speed of movement of the laser beam as well as the power density are preferably similar from one pass to the next. Of course, it is possible to change these irradiation parameters, for example by programming a higher or lower movement speed than that used in the first pass.

[0342] Preferably, the laser beam 35 can pass between 2 and 20 times, preferably between 3 and 10 times, over the treated area 45. In the example illustrated, the laser beam 35 makes three passes over the treated area 45 during the fixing step 104.

[0343] If the processing step 202 and the deposition step 206 are carried out by two different and removable devices, then the processing step 202 and / or the fixing step 206 comprise a wedging of the processing device 80 and / or the laser device 30 before carrying out these steps using the positioning means 12.

[0344] The method 200 optionally comprises a step 208 of removing the marking composition 2 not irradiated in the fixing step 206.

[0345] The removal step 208 may be performed manually or via the cleaning device 60 as described above.

[0346] It can be seen in Figure 8 that the metal layer 44 of the substrate 42 comprises a colored marking only on the treated area 45. Thus, in this example, a colored pattern is obtained on the metal layer 44 following the method 200. The other portions of the substrate 42 have not been marked (or pigmented or colored) by the marking composition 2.

[0347] Thus, in the removal step 208, the non-irradiated portions of the marking composition 2 in the fixing step 206 and / or the portions of the marking composition irradiated in the fixing step 206 but not positioned on the treated area 45 of the metal layer 44 are removed. A colored pattern 24 is obtained on the surface of the metal layer 44.

[0348] Thus, the method 200 allows the fixing of a marking composition 2 on a substrate 42 having a metal layer 44. As explained above, the marking composition 2 can be of different types and use various coloring agents to pigment (or color) the metal layer 44 with a desired color.

[0349] Table 3 shows results of a substrate 42 with a metal layer 44 having an area colored (i.e. marked) by different colors by implementing the method 200 described above.

[0350] In this example, the fixing step 206 can be carried out with a laser beam emitting at 355 nm and having a power density typically comprised here between 32 W / mm 2 and 208 W / mm2. The laser beam travel speed for these two stages was between 50 mm. s -1 and 500 mm. s -1 and for a single pass of the laser beam over the surface of the substrate to be marked.

[0351] [Table 3] metallic 44 having a colored area (ie marked) by different colors by implementing the method 200 described above.

[0353] In this example, the fixing step 206 can be carried out with a CO2 laser beam emitting at 10600 nm and having a power density of between 60W / mm 2 and 5kW / mm 2 The laser beam travel speed for these two steps was between 0.1 m.s' 1 and 9.0 m.s' 1 for a number of passages of the laser beam between 1 and 20.

[0354] [Table 4] 0355] Examples of substrates having a metal face marked by the method 200 will then be described.

[0356] The metal layer suitable for being marked by the method 200 comprises at least one of the following materials: a pure metal such as zinc, aluminum, copper, gold, silver; a treated (oxidized) metal such as anodized aluminum, a metal alloy such as brass or steel or stainless steel (also called stainless steel), ferrous metals, zamak type alloy (alloy of zinc, aluminum and optionally copper). Of course, in one embodiment, the metal layer may be covered by a protective layer as described above.

[0357] The results obtained presented below were obtained with flat substrates having an average roughness of less than 2.00 cm. The marking composition used is similar to that used in Table 1 and Table 2 described above.

[0358] The fixation step was carried out with one of the lasers described below for a power density between 32 W / mm 2 and 7.7 kW / mm 2 and at a speed, measured relative to the substrate, of between 10 mm. s -1 and 9.0 m.s' 1 . In a way advantageously, better results are obtained when the processing step is carried out with a power density of 955 W / mm 2 and 1,277 kW / mm 2 and a travel speed of 500 mm. s -1 and 900 mm. s -1 with a number of passes n of 1 and for a CO2 laser emitting at 10600 nm.

[0359] Table 5 0360] The solid-state amplifying medium lasers used described in this Table 5 are similar to those described above (device) and were obtained with a single pass of the laser beam at the fixing step 206 or multiple passes of the laser beam at the fixing step 206.

[0361] Variants

[0362] The present invention is in no way limited to the embodiments described and shown, but those skilled in the art will be able to provide any variation in accordance with the invention.

Claims

DEMANDS

1. A method for fixing a marking composition (2) onto a substrate (4, 42) by laser irradiation, the marking composition (2) comprising at least one coloring agent, the method comprising the following steps: - deposition (102, 204) of the marking composition (2) on at least a portion of the substrate (4, 42); - fixation (104, 206) of a part of the marking composition (2) by moving a laser beam (35) to irradiate at least a part of the marking composition deposited on the substrate (4, 42), - elimination (106,208) of the marking composition (2) not irradiated at the fixation step (104, 206), characterized in that the laser beam (35) has a power density between 32 W / mm 2 and 7.7 kW / mm² 2in contact with the irradiated marking composition (2) and in that the displacement of the laser beam is carried out at a speed, measured relative to the substrate, of between 10 mm. s -1 and 9.0 m.s' 1 .

2. The method according to claim 1, characterized in that the power density is between 60 W / mm² 2 and 5 kW / mm 2 and in that the laser beam is displaced at a speed between 0.1 m / s -1 and 9.0 m / s -1 .

3. A method according to claim 1 or 2, characterized in that the fixing step is carried out on a face of the substrate (3, 43), called the marking face, comprising a metallic layer, the method comprising, before the deposition step (102, 204), a treatment step (202) of at least one area of ​​the metallic layer (44) by laser irradiation, the deposition (204) and fixing (206) steps being carried out on the treated area (45) of the metallic layer (44).

4. A method according to claim 3, characterized in that the processing step (202) uses a laser emitting a laser beam, the laser beam used in the processing step (202) and the laser beam used in the fixation step (206) have at least one identical property, at least one property comprising at least one of the following elements: - wavelength; - power density; - speed of movement.

5. A method according to any one of claims 3 to 4, characterized in that the treated area (45) has a surface exhibiting one of the following colors: - a white color; - a color in shades of grey.

6. A method according to any one of claims 1 to 5, characterized in that the substrate (4, 42) comprises at least one of the following elements: - metal; - plastic; - a composite; - an organic material of plant origin; - an organic material of animal origin; - a synthetic material; - a cellulosic material; - a mixture or assembly of several of the preceding materials.

7. A method according to any one of claims 1 to 6, characterized in that, during the fixing step (104, 206), said laser is configured to pass n times over said part of the marking composition (2), with n greater than or equal to 2.

8. A method according to any one of claims 1 to 7, characterized in that the substrate (4, 42) has a roughness between 0 micrometers and 2 centimeters.

9. A method of any one of claims 1 to 8, characterized in that the laser (31) is coupled with a focusing device (33) having a focal length for focusing the laser beam (35) to a focal point, the substrate (4, 42) being located at the focal point or at a distance from the point focal length less than or equal to 5 cm.

10. A method according to any one of claims 1 to 9, characterized in that the laser (31) used in the fixation step (104, 206) comprises at least one of the following lasers: - a YAG laser emitting a laser beam at an emission wavelength of 1064 nanometers, - a CO2 laser emitting a laser beam at an emission wavelength of 10600 nanometers, - a doubled YAG laser emitting a laser beam at an emission wavelength of 532 nanometers. - a triple YAG laser emitting a laser beam at an emission wavelength of 355 nanometers.

11. Method according to claim 10, characterized in that, when the laser beam is a YAG laser, the generated laser beam (31) is a pulsed laser beam (31), and when the laser beam is a CO2 laser, the generated laser beam (31) is a continuous laser beam (31).

12. A method according to any one of claims 1 to 11, characterized in that the marking composition (2) comprises: - an aqueous base, - at least one coloring agent in the aqueous base.

13. A process according to any one of claim 12, characterized in that the aqueous base comprises water with a short-chain alcohol or an acrylic binder mixed with a surfactant.

14. A method according to any one of claims 12 to 13, characterized in that the coloring agent is selected from: - a pigment comprising at least one of the following elements: a metallic oxide, a metal, a metallic alloy, a metallic alloy oxide; - an inorganic pigment; - an organic pigment; - a pigment comprising a carbonate mineral; - sodium aluminosilicate thiosulfate; - a synthetic dye; - a natural dye; or mixtures thereof.

15. A process according to claim 14, characterized in that the coloring agent further comprises a silicate in the form of particles comprising 38% to 74% by weight in the composition of the coloring agent.

16. A method according to any one of claims 1 to 15, characterized in that the marking composition (2) fixed on said substrate (4, 42) has a thickness between 10 nanometers and 0.1 millimeters.

17. A method according to any one of claims 1 to 16, characterized in that, where the coloring agent comprises at least one pigment, each pigment being in the form of particles of size between 10 nm and 0.2 mm.

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