Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
  • B05D3/06—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by exposure to radiation
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F26—DRYING
  • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
  • F26B3/00—Drying solid materials or objects by processes involving the application of heat
  • F26B3/28—Drying solid materials or objects by processes involving the application of heat by radiation, e.g. from the sun
  • F26B3/30—Drying solid materials or objects by processes involving the application of heat by radiation, e.g. from the sun from infrared-emitting elements
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
  • B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
  • B23K26/073—Shaping the laser spot
  • B23K26/0738—Shaping the laser spot into a linear shape
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/08—Devices involving relative movement between laser beam and workpiece
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/08—Devices involving relative movement between laser beam and workpiece
  • B23K26/083—Devices involving movement of the workpiece in at least one axial direction
  • B23K26/0838—Devices involving movement of the workpiece in at least one axial direction by using an endless conveyor belt
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C17/00—Surface treatment of glass, not in the form of fibres or filaments, by coating
  • C03C17/28—Surface treatment of glass, not in the form of fibres or filaments, by coating with organic material
  • C03C17/32—Surface treatment of glass, not in the form of fibres or filaments, by coating with organic material with synthetic or natural resins
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D2203/00—Other substrates
  • B05D2203/30—Other inorganic substrates, e.g. ceramics, silicon
  • B05D2203/35—Glass
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D2502/00—Acrylic polymers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D2503/00—Polyurethanes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
  • B05D3/02—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by baking
  • B05D3/0254—After-treatment
  • B05D3/0263—After-treatment with IR heaters
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D5/00—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures
  • B05D5/06—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures to obtain multicolour or other optical effects
  • B05D5/061—Special surface effect
  • B05D5/063—Reflective effect
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C2218/00—Methods for coating glass
  • C03C2218/30—Aspects of methods for coating glass not covered above
  • C03C2218/32—After-treatment

Definitions

• the invention relates to the field of substrate painting and describes a method of drying and / or cooking by laser especially suitable for paints or inks comprising an organic solvent or aqueous based.
• the paints are then dried and / or baked or in an oven.
• Three main techniques are currently available to ensure this drying and / or cooking: drying in ambient air, drying / baking, UV crosslinking.
• the running speed of substrates coated with paint in a drying oven or oven or firing can range from a few 1 m / min for glass substrates to 1 km / min in the case of press presses for example.
• UV crosslinking cooking is carried out purely by photochemical means by irradiating the paint with UV radiation causing crosslinking.
• This technique allows higher rates than drying / baking but causes environmental problems, particularly because of the significant generation of ozone, acrylates and free radicals in the production area.
• the present invention proposes to combine the power of intense radiation of the laser type (which of course covers the possibility of having several such radiations) with traditional paints or inks for a baking process.
• the invention is particularly suitable for the heat treatment of coated substrates having large areas, in particular ranging from 1 to 25 m 2 .
• the invention relates to a method for heating an organic coating applied to substrates, wherein laser radiation is applied to the organic coating while the substrates are continuously moving.
• the coating is organic to the extent that it comprises at least one organic compound before the laser treatment according to the invention.
• a paint commonly used to protect the backs of mirrors is an organic coating because it contains an organic solvent or an organic resin.
• the coating may comprise an organic pigment. After treatment with the process according to the invention, the coating generally still contains an organic compound.
• the invention is particularly suitable for drying or baking paints applied to a glass substrate such as the back of mirrors, especially in the latter case to protect the silver layer from corrosion.
• the laser treatment according to the invention also has the particularity, unlike the annealing or quenching treatments, of not significantly heating the substrate. It is thus not necessary to carry out a slow and controlled cooling of the coated substrate before it is cut or stored.
• This method also makes it possible to integrate a heating device on existing continuous production lines, in particular a mirror production line, which may include a silver layer preheating zone to eliminate traces of moisture.
• the substrate may in particular comprise or be a glass sheet, glass-ceramic, or an organic polymer.
• it is transparent preference. It can be colorless (it is then a clear or extraclear glass) or colored, for example in blue, green, gray or bronze.
• the glass is preferably of the silico-soda-lime type, but it may also be of borosilicate or alumino-borosilicate type glass.
• the preferred organic polymers are polycarbonate or polymethylmethacrylate or polyethylene terephthalate (PET).
• PET polyethylene terephthalate
• the substrate may have at least one dimension greater than or equal to 1 m, or even 2 m and even 3 m.
• the thickness of the substrate is generally from 0.5 mm to 20 mm, in particular for the mirror application from 0.7 to 9 mm, in particular from 2 to 8 mm, or even from 4 to 6 mm.
• the substrate may be flat or curved. It can be rigid or flexible.
• the glass substrate is generally of the float type, that is to say likely to have been obtained by a process of pouring the molten glass on a bath of molten tin ("float" bath).
• the layer to be treated may be deposited on the "tin” side as well as on the "atmosphere” side of the substrate.
• the term "atmosphere” and “tin” faces means the faces of the substrate having respectively been in contact with the atmosphere prevailing in the float bath and in contact with the molten tin.
• the tin side contains a small surface amount of tin that has diffused into the glass structure.
• the glass substrate can also be obtained by rolling between two rollers, a technique which makes it possible in particular to print patterns on the surface of the glass.
• the substrate may in particular be of the glass type, coated with ink (comprising at least one pigment, in particular in the form of nanoparticles or comprising at least one organic dye) or organic solvent-based paint, hydro diluted or even water-soluble.
• ink comprising at least one pigment, in particular in the form of nanoparticles or comprising at least one organic dye
• organic solvent-based paint hydro diluted or even water-soluble.
• the invention is particularly suitable for inks and paints of alkyd, acrylic and polyurethane type but not exclusively.
• the temperature ranges accessible by the technique according to the invention are particularly suitable for technologies based on urea / formaldehyde, epoxide or isocyanate crosslinking mechanisms, but not exclusively.
• the heat treatment is carried out using at least one laser radiation.
• the pfd of the laser radiation at the coating is preferably greater than or equal to 20 and even greater than or equal to 30 kW / cm 2 .
• This very high energy density makes it possible to reach the desired temperature very rapidly at the coating level (generally in a time of less than or equal to 1 second) and consequently to limit the duration of the treatment by as much, the heat generated as then having no time to diffuse within the substrate.
• the portion of the substrate (particularly glass) located at 0.5 mm from the coating does not generally undergo temperatures above 100 ° C.
• the substrate therefore does not generally undergo a temperature greater than 100 ° C at a depth of 0.5 mm from the substrate / coating interface.
• the coating undergoes a uniform temperature that allows drying or baking of paints or inks without inducing defects.
• the method according to the invention is continuous: a relative movement is created between the coated substrate and the laser beam heating means so as to treat the desired surface, in general the entire surface.
• the laser radiation preferably has a wavelength of between 266 and 1000 nm, especially between 530 and 1200 nm. It is indeed in this range of wavelengths that the absorption of the coating (paint or ink) is maximum. Thus the radiation is absorbed specifically by the coating and little by the substrate, which allows to quickly heat the layer without heating the substrate.
• glass especially clear or extra-clear glass, absorbs very little in this range of wavelengths so that the radiation mainly heats the layer.
• the absorption is defined as being equal to the value of 100% to which the transmission and the reflection of the layer are subtracted.
• Laser diodes emitting for example at a wavelength of the order of 808 nm, 880 nm, 940 nm, or 980 nm or 1032 nm, are preferably used.
• very high powers can be obtained, making it possible to achieve surface powers at the level of the layer to be treated greater than 20 kW / cm 2 , or even greater than 30 kW / cm 2 .
• the lasers used in the context of the invention can be fiber-reinforced, which means that the laser radiation (any gain medium: gas, liquid, solid) is injected into an optical fiber and then delivered near the surface to be treated by a focusing head.
• the laser can also be fiber, in the sense that the amplification medium (that is to say gain medium) is itself an optical fiber, generally doped with rare earth ions ("fiber laser " in English)
• the laser radiation may be from at least one laser beam forming a line (called "laser line” in the rest of the text) which simultaneously radiates the entire width of the substrate coated with the coating to be heated.
• laser line a line
• the in-line laser beam can in particular be obtained using high power laser diode systems associated with focusing optics.
• the thickness of the line is preferably between 0.01 and 1 mm.
• the length of the line is adapted to the width of the substrate to be treated, it is typically between 5 mm and 4 m.
• the intensity profile of the line (in its width) can in particular be a Gauss curve or a slot.
• the laser radiation is applied along a line substantially transverse to the direction of travel of the substrates.
• the laser line simultaneously radiating all or part of the width of the substrates may be composed of a single line (then radiating the entire width of the substrate), or of several lines, possibly disjointed. When several lines are used, it is preferable that they are arranged so that the entire surface of the coating to be heated is treated.
• the laser line can be arranged obliquely to the direction of travel of the substrate, but is preferably disposed perpendicular to the running direction of the substrate. In the case of several laser lines, these can process the substrate simultaneously or in a time-shifted manner.
• different laser beams are either physically focused in the same place to have a simultaneous treatment of the substrate, or they are shifted in space to treat one by one a given width of the moving substrate. The important thing is that the entire surface to be treated is.
• a relative displacement is applied between the substrate coated with the layer and the laser line.
• the substrate coated with the layer to be treated by laser can thus be set in motion, in particular in translation translation with respect to the fixed laser line, generally below, but possibly above the laser line.
• the difference between the respective speeds of the substrate and the laser is greater than or equal to 1 meter per minute, or even 4 and even 6, 8, 10 or 20 meters per minute, in order to ensure a high processing speed.
• the substrates scroll at a speed of 1 to 20 meters per minute.
• the setting in motion can be carried out using any mechanical means of conveying, for example using strips, rollers, trays in translation.
• the conveyor system controls and controls the speed of travel.
• the substrate is of flexible organic material, generally of the polymer type such as PVC or PTFE
• the displacement can be achieved using a film feed system comprising a succession of rollers.
• the laser may also be moved to adjust its distance to the substrate, which may be useful especially when the substrate is curved, but not only. Indeed, it is preferable that the laser beam is focused on the coating to be treated so that the latter is located at a distance less than or equal to 1 mm of the focal plane. Ideally, the coating merges with the focal plane. If the substrate or laser displacement system is not sufficiently precise as to the distance between the substrate and the focal plane, it is preferable to be able to adjust the distance between the laser and the substrate. This adjustment can be automatic, in particular regulated by measuring the distance upstream of the treatment.
• the substrate is generally arranged horizontally, but it can also be arranged vertically, or in any possible inclination.
• the laser is generally arranged to irradiate the upper face of the substrate.
• the on-line laser can be integrated into a lacquered glass production line or mirrors, in particular solar mirrors.
• the on-line laser is located in the production process after the silvering steps, for example as a preheating element of the glass before depositing a layer of paint or just after the deposition of this layer .
• the coated substrate can thus be treated in line after the deposition of the layer to be treated (ink or paint), at the exit of the deposition installation and before the optical control devices, or after the optical control devices and before the devices for stacking substrates.
• a laser line as for example described in FIG. 1 makes it possible to heat a coating (ink or paint) with a thickness of generally between 1 ⁇ and 200 ⁇ extremely rapidly before laser treatment (that is to say heating) according to FIG. the invention.
• Inks and paints used for baking are naturally very absorbent in the infrared, a laser typically emitting in a wavelength range of 266 nm to 1 1000 nm and allows an optimal transfer of energy between the source of radiation and the layer of paint.
• the laser heating method according to the invention can in particular be used in four main modes: drying, rapid rise in temperature, baking or powder coating:
• drying mode in this case, the laser irradiation makes it possible to very rapidly transfer energy corresponding to the latent heat of vaporization (L) of the solvent to be volatilized; in this case, a strong air flow ensures the extraction of the solvent vapors; - rapid temperature rise: after drying, the coating (paint or lacquer or ink) retains its absorbent properties in the infrared; the laser treatment then allows an extremely fast rise of the dry coating for subsequent cooking in a baking oven; the drying itself can be carried out in an oven or by the treatment according to the invention, the drying being followed by a heat treatment by laser according to the invention;
• - powder coating the application of a powder coating allows the use of a single treatment with a laser beam to melt the powder and then harden it.
• the laser treatment according to the invention makes it possible to heat the coating mainly by heating the substrate to a minimum. This therefore makes it possible to reduce the total energy required to treat the coating and / or to increase the treatment rates.
• the process according to the invention can be used for drying or baking paints for indoor or solar mirrors, and also for finishing the paint of a lacquered glass.
• the method according to the invention can be used to shorten the lengths of drying or cooking ovens.
• the laser treatment according to the invention provides for the removal of a combustible organic material (a solvent for example) from the coating, it is possible to ensure dilution and sufficient convection with the aid of a gas such as air above the coated substrate to thereby reduce the risk of ignition or explosion.
• a combustible organic material a solvent for example
• P [W / m 2 ] power density of the laser radiation
• L [m] length of the beam or of all the laser beams
• p density of the wet or dry coating layer respectively according to whether it is dried (solvent evaporation) or baked coating (no solvent evaporation)
• V speed of travel of the substrate
• Figure 1 shows the method according to the invention.
• Substrates 1 coated with a coating to be dried or cooked, run one behind the other continuously in a direction represented by the arrow, being conveyed by a bed of rollers (not shown). They pass under a laser source 2 which delivers a laser line 3 focused on the surface of the moving substrates and along their entire width. The laser line produces heating to dry or bake the coating.
• a drying according to the invention of a layer of paint deposited on the back of the mirror as a protective coating.
• the coating before drying had a thickness of 50 ⁇ , a density of 2 T / m 3 , a heat capacity of 0.7 kJ / Kg / K, an absorbance of 1.
• the density of the coating is 1, 3 T / m 3 and each KW / m 2 leads to an increase in the paint temperature of 4 Kelvin.
• the laser radiation essentially heats the coating, the glass being heated solely by conduction from the coating and in a very short time ( ⁇ 1 s) limiting the increase in its average temperature to less than 1 K on its total thickness.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Plasma & Fusion (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Microbiology (AREA)
• General Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Surface Treatment Of Glass (AREA)
• Coating Apparatus (AREA)

Applications Claiming Priority (2)

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Family Applications (1)

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Cited By (1)

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Citations (3)

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• 2011
  • 2011-02-25 FR FR1151576A patent/FR2971960B1/fr not_active Expired - Fee Related
• 2012
  • 2012-02-21 CN CN201280010462.0A patent/CN103379980B/zh not_active Expired - Fee Related
  • 2012-02-21 EA EA201391227A patent/EA027409B1/ru not_active IP Right Cessation
  • 2012-02-21 CA CA2826149A patent/CA2826149A1/fr not_active Abandoned
  • 2012-02-21 KR KR1020137021998A patent/KR20140005262A/ko not_active Application Discontinuation
  • 2012-02-21 US US14/001,178 patent/US20140059878A1/en not_active Abandoned
  • 2012-02-21 WO PCT/FR2012/050365 patent/WO2012114038A1/fr active Application Filing
  • 2012-02-21 EP EP12709945.5A patent/EP2678132A1/fr not_active Withdrawn
  • 2012-02-21 BR BR112013020034A patent/BR112013020034A2/pt not_active IP Right Cessation
  • 2012-02-21 JP JP2013554928A patent/JP5902721B2/ja not_active Expired - Fee Related
  • 2012-02-21 AU AU2012220431A patent/AU2012220431B2/en not_active Ceased
  • 2012-02-21 MX MX2013009726A patent/MX362398B/es active IP Right Grant

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