EP1413841A1 - Process for drying a coating on a metal strip - Google Patents

Process for drying a coating on a metal strip Download PDF

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Publication number
EP1413841A1
EP1413841A1 EP03292565A EP03292565A EP1413841A1 EP 1413841 A1 EP1413841 A1 EP 1413841A1 EP 03292565 A EP03292565 A EP 03292565A EP 03292565 A EP03292565 A EP 03292565A EP 1413841 A1 EP1413841 A1 EP 1413841A1
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EP
European Patent Office
Prior art keywords
solvents
oven
coating
gas
temperature
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Application number
EP03292565A
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German (de)
French (fr)
Inventor
Ernesto Lopez
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Myriad
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Myriad
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Publication date
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Publication of EP1413841A1 publication Critical patent/EP1413841A1/en
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • F26B3/32—Drying solid materials or objects by processes involving the application of heat by development of heat within the materials or objects to be dried, e.g. by fermentation or other microbiological action
    • F26B3/34—Drying solid materials or objects by processes involving the application of heat by development of heat within the materials or objects to be dried, e.g. by fermentation or other microbiological action by using electrical effects
    • F26B3/343—Drying solid materials or objects by processes involving the application of heat by development of heat within the materials or objects to be dried, e.g. by fermentation or other microbiological action by using electrical effects in combination with convection
    • 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
    • B05D3/0281—After-treatment with induction heating
    • 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
    • B05D2202/00—Metallic substrate
    • 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
    • B05D2252/00—Sheets
    • B05D2252/02—Sheets of indefinite length

Definitions

  • the present invention relates to a method of depositing and drying a protective coating on a continuously moving metal strip.
  • This is in particular the application of a coat of paint.
  • This contains organic or aqueous solvents and, after the deposition of the paint layer on the strip, the assembly is heated in order to facilitate the evaporation of the solvents and to allow the paint to cook.
  • the heating of the strip is, in the case of the invention, carried out by electromagnetic induction with the advantage of heating the paint by the substrate (that is to say by the strip), the heat flux propagating towards the outside, which facilitates the evaporation of solvents.
  • the equipment used in the invention is well known, in particular from the documents cited above.
  • a tunnel oven comprising an outer casing and through which the metal strip to be provided with a protective or decorative coating, moves continuously.
  • This oven is heated by magnetic induction.
  • This induction heating ensures, in a known manner, on the one hand the cooking of the coating previously deposited on the strip and on the other hand, the evaporation of the solvents contained in the coating material.
  • a hot gas is injected into the tunnel, at the inlet, at the outlet of the oven and in several places along the latter so as to ensure a homogeneous dilution of the solvents and a uniform temperature throughout the installation.
  • the oven has a system for extracting the atmosphere from the oven loaded with solvents.
  • the extraction of the atmosphere loaded with solvents can be carried out either at a single point or at several points.
  • extraction is carried out, preferably between two inductors.
  • the extracted solvents are used to preheat the gas injected in a known manner into a solvent incinerator.
  • the oven is waterproof with respect to solvents, transparent to the magnetic field and has good thermal insulation and good mechanical strength.
  • the temperature for reheating the gas injected into the oven is chosen to be much higher than the dew point of the solvents to avoid the formation in the solvent extraction ducts, or even of the gas injection, the formation of a clogging deposit as recalled in the preamble.
  • This temperature will be such that the atmosphere in the oven and in the conduits will be at least 175 ° C, and preferably between 180 ° C and 220 ° C. It has been found that at this temperature the phenomenon of depositing an organic solid compound against the internal surface of the oven and of the extraction pipes for gases loaded with solvents is avoided. Of course, this temperature cannot be excessively high because the integrity of the equipment in the oven and in particular of the components of the inductors must be respected.
  • the invention makes it possible to very significantly improve the cleanliness of the oven, which reduces the frequency of maintenance operations linked to cleaning the oven. and keeping the installation's safety equipment, particularly fire safety, in operation.

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  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Microbiology (AREA)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
  • Biotechnology (AREA)
  • Molecular Biology (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Drying Of Solid Materials (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Coating Apparatus (AREA)

Abstract

The process involves heating a protective or decorative paint coated metal strip by an electromagnetic induction in a wedge furnace to vaporize solvents and ensure firing of the coating. The solvents are continuously extracted inside the furnace by injecting a gas at a temperature between 180 and 220 degree celsius which is higher than a solvent dew temperature that prevails inside the furnace atmosphere and extraction ducts.

Description

La présente invention concerne un procédé de dépôt et de séchage d'un revêtement protecteur sur une bande métallique se déplaçant de façon continue.The present invention relates to a method of depositing and drying a protective coating on a continuously moving metal strip.

ARRIERE-PLAN DE L'INVENTIONBACKGROUND OF THE INVENTION

Il s'agit en particulier de l'application d'une couche de peinture. Celle-ci contient des solvants organiques ou aqueux et, après le dépôt de la couche de peinture sur la bande, l'ensemble est chauffé afin de faciliter l'évaporation des solvants et de permettre la cuisson de la peinture. Le chauffage de la bande est, dans le cas de l'invention, réalisé par induction électromagnétique avec l'avantage de chauffer la peinture par le substrat (c'est-à-dire par la bande), le flux thermique se propageant vers l'extérieur, ce qui facilite l'évaporation des solvants. Pour éviter une recondensation des solvants évaporés sur les parties les plus froides des parois du four, dont la température est en général inférieure au point de rosée des solvants, on a proposé d'injecter dans le four un gaz chaud de façon que les parois internes dudit four soient à une température supérieure au point de rosée des solvants et de rendre le four étanche aux gaz et isolé thermiquement pour conserver des parois internes chaudes au-dessus de ce point de rosée (voir par exemple les brevets US 4 370 357 et 5 768 799.This is in particular the application of a coat of paint. This contains organic or aqueous solvents and, after the deposition of the paint layer on the strip, the assembly is heated in order to facilitate the evaporation of the solvents and to allow the paint to cook. The heating of the strip is, in the case of the invention, carried out by electromagnetic induction with the advantage of heating the paint by the substrate (that is to say by the strip), the heat flux propagating towards the outside, which facilitates the evaporation of solvents. To avoid recondensation of the solvents evaporated on the coldest parts of the walls of the oven, the temperature of which is generally lower than the dew point of the solvents, it has been proposed to inject a hot gas into the oven so that the internal walls of said oven are at a temperature above the dew point of the solvents and to make the oven gas-tight and thermally insulated to keep the internal walls hot above this dew point (see for example US Pat. Nos. 4,370,357 and 5 768,799.

A l'usage, on a constaté, aux températures de fonctionnement préconisées par les constructeurs, qui sont les températures les plus basses au-dessus du point de rosée (100 à 120°C), la formation de composés organiques solides qui se déposent dans le four et les conduits d'extraction des solvants. Ces dépôts constituent une entrave au bon fonctionnement de l'installation et notamment aux composants de celle-ci qui sont nécessaires à sa sécurité (vannes coupe-feu, aérateurs, vannes de dérivation...) et demandent une maintenance soutenue qui constitue une gêne à l'exploitation optimale de l'installation. Ces composés ont probablement pour origine des réactions entre les solvants et les bases époxy ou polyester, PVC et/ou polyuréthanne des peintures dues aux conditions thermiques entretenues dans l'atmosphère du fourIn use, it has been found, at the operating temperatures recommended by the manufacturers, which are the lowest temperatures above the dew point (100 to 120 ° C.), the formation of solid organic compounds which are deposited in the oven and the solvent extraction pipes. These deposits constitute an obstacle to the proper functioning of the installation and in particular to the components of the latter which are necessary for its safety (fire stop valves, aerators, bypass valves, etc.) and require sustained maintenance which constitutes a hindrance. to the optimal exploitation of the installation. These compounds probably originate from reactions between solvents and epoxy or polyester, PVC and / or polyurethane bases in paints due to the thermal conditions maintained in the atmosphere of the oven.

OBJET DE L'INVENTIONOBJECT OF THE INVENTION

Pour pallier cet inconvénient, on propose, conformément à l'invention, d'entretenir à l'intérieur du four et dans les canaux d'extraction et d'injection de gaz (par exemple de l'air chaud) une température supérieure à 150°C et de préférence comprise entre 180°C et 220°C.To overcome this drawback, it is proposed, in accordance with the invention, to maintain inside the oven and in the gas extraction and injection channels (for example hot air) a temperature above 150 ° C and preferably between 180 ° C and 220 ° C.

D'autres caractéristiques et avantages de la présente invention ressortiront de la description faite ci-après d'un exemple de réalisation dépourvu de tout caractère limitatif.Other characteristics and advantages of the present invention will emerge from the description given below of an exemplary embodiment devoid of any limiting character.

DESCRIPTION DETAILLEE DE L'INVENTIONDETAILED DESCRIPTION OF THE INVENTION

Le matériel mis en oeuvre dans l'invention est bien connu notamment des documents précédemment cités. C'est ainsi qu'il comporte un four tunnel comportant une enveloppe extérieure et au travers duquel la bande métallique devant être munie d'un revêtement protecteur ou décoratif, se déplace en continu. Ce four est chauffé par induction magnétique. Ce chauffage par induction assure, de façon connue, d'une part la cuisson du revêtement préalablement déposé sur la bande et d'autre part, l'évaporation des solvants contenus dans le matériau de revêtement.The equipment used in the invention is well known, in particular from the documents cited above. Thus it comprises a tunnel oven comprising an outer casing and through which the metal strip to be provided with a protective or decorative coating, moves continuously. This oven is heated by magnetic induction. This induction heating ensures, in a known manner, on the one hand the cooking of the coating previously deposited on the strip and on the other hand, the evaporation of the solvents contained in the coating material.

On injecte un gaz chaud dans le tunnel, à l'entrée, à la sortie du four et à plusieurs endroits le long de celui-ci de manière à assurer une dilution homogène des solvants et une température homogène dans toute l'installation.A hot gas is injected into the tunnel, at the inlet, at the outlet of the oven and in several places along the latter so as to ensure a homogeneous dilution of the solvents and a uniform temperature throughout the installation.

Le four comporte un système d'aspiration de l'atmosphère du four chargée en solvants. L'extraction de l'atmosphère chargée en solvants peut s'effectuer soit en un point unique, soit en plusieurs points. Lorsque le four comprend plusieurs inducteurs séparés, l'extraction est menée, de préférence entre deux inducteurs.The oven has a system for extracting the atmosphere from the oven loaded with solvents. The extraction of the atmosphere loaded with solvents can be carried out either at a single point or at several points. When the oven includes several separate inductors, extraction is carried out, preferably between two inductors.

Les solvants extraits sont utilisés pour préchauffer le gaz injecté de manière connue dans un incinérateur de solvants.The extracted solvents are used to preheat the gas injected in a known manner into a solvent incinerator.

Le four est étanche vis à vis des solvants, transparent au champ magnétique et présente une bonne isolation thermique et une bonne tenue mécanique.The oven is waterproof with respect to solvents, transparent to the magnetic field and has good thermal insulation and good mechanical strength.

Selon l'invention, la température de réchauffage du gaz injecté dans le four est choisie très supérieure au point de rosée des solvants pour éviter la formation dans les conduits d'extraction des solvants, voire d'injection du gaz, la formation d'un dépôt colmatant comme rappelé au préambule. Cette température sera telle que l'atmosphère dans le four et dans les conduits sera au minimum de 175°C, et de préférence comprise entre 180°C et 220°C. On a constaté qu'à cette température on évite le phénomène de dépôt d'un composé solide organique contre la surface interne du four et des canalisations d'extraction des gaz chargés de solvants. Bien entendu cette température ne peut pas être exagérément élevée car il convient de respecter l'intégrité du matériel dans le four et notamment des composants des inducteurs.According to the invention, the temperature for reheating the gas injected into the oven is chosen to be much higher than the dew point of the solvents to avoid the formation in the solvent extraction ducts, or even of the gas injection, the formation of a clogging deposit as recalled in the preamble. This temperature will be such that the atmosphere in the oven and in the conduits will be at least 175 ° C, and preferably between 180 ° C and 220 ° C. It has been found that at this temperature the phenomenon of depositing an organic solid compound against the internal surface of the oven and of the extraction pipes for gases loaded with solvents is avoided. Of course, this temperature cannot be excessively high because the integrity of the equipment in the oven and in particular of the components of the inductors must be respected.

Ainsi, en dehors de la suppression des recondensations des solvants, qui permet de maintenir la qualité du produit revêtu, l'invention permet d'améliorer très sensiblement la propreté du four, ce qui diminue la fréquence des opérations de maintenance liées au nettoyage du four et au maintien en fonctionnement des équipements de sécurité de l'installation notamment de sécurité incendie.Thus, apart from eliminating the recondensations of the solvents, which makes it possible to maintain the quality of the coated product, the invention makes it possible to very significantly improve the cleanliness of the oven, which reduces the frequency of maintenance operations linked to cleaning the oven. and keeping the installation's safety equipment, particularly fire safety, in operation.

Claims (5)

Procédé de revêtement par peinture d'une bande métallique en déplacement continu selon lequel ladite bande, après avoir reçu son revêtement, est chauffée par induction électromagnétique dans un four tunnel pour évaporer les solvants et assurer la cuisson du revêtement, les solvants étant extraits en continu de l'enceinte dudit four, caractérisé en ce qu'on injecte dans le four un gaz à une température supérieure au point de rosée des solvants, température telle que la température régnant dans l'atmosphère du four et au moins dans les conduits d'extraction des solvants est au moins égale à 175°C.Method for coating with paint a continuously moving metal strip in which said strip, after having received its coating, is heated by electromagnetic induction in a tunnel oven to evaporate the solvents and ensure the baking of the coating, the solvents being continuously extracted of the enclosure of said oven, characterized in that a gas is injected into the oven at a temperature above the dew point of the solvents, temperature such as the temperature prevailing in the atmosphere of the oven and at least in the conduits of solvent extraction is at least 175 ° C. Procédé selon la revendication 1, caractérisé en ce que le gaz est injecté à une température supérieure à 180°C.Method according to claim 1, characterized in that the gas is injected at a temperature above 180 ° C. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que la température d'injection du gaz est comprise entre 180°C et 220°C.Process according to any one of the preceding claims, characterized in that the gas injection temperature is between 180 ° C and 220 ° C. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que le gaz est de l'air chaud.Method according to any one of the preceding claims, characterized in that the gas is hot air. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce que le gaz injecté est préalablement réchauffé dans un incinérateur des solvants.Method according to any one of the preceding claims, characterized in that the injected gas is previously reheated in a solvent incinerator.
EP03292565A 2002-10-25 2003-10-15 Process for drying a coating on a metal strip Withdrawn EP1413841A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR0213366 2002-10-25
FR0213366A FR2846261B1 (en) 2002-10-25 2002-10-25 METHOD FOR DRYING A METAL TAPE COATING

Publications (1)

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EP1413841A1 true EP1413841A1 (en) 2004-04-28

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FR (1) FR2846261B1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012163334A1 (en) * 2011-05-27 2012-12-06 Thermprotec Gmbh Method and assembly for producing a coated metal strip

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2833672A (en) * 1955-05-17 1958-05-06 United States Steel Corp Method and apparatus for continuously applying a protective film of lacquer to steelstrip
US4370357A (en) * 1981-03-11 1983-01-25 Cleveland Gear Company Process of continuous metal coating
US4594266A (en) * 1983-07-14 1986-06-10 Cockerill Sambre S.A. Process and an apparatus for baking an organic coating which has been applied to a substrate
US5041312A (en) * 1990-02-13 1991-08-20 Swartz Leroy Apparatus and method for coating a metal strip
US5768799A (en) * 1995-05-23 1998-06-23 Stein Heurtey Process and apparatus for coating metal sheets
US5895599A (en) * 1996-08-02 1999-04-20 Selas S.A. Induction heating device and continuous treatment installation including same

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2833672A (en) * 1955-05-17 1958-05-06 United States Steel Corp Method and apparatus for continuously applying a protective film of lacquer to steelstrip
US4370357A (en) * 1981-03-11 1983-01-25 Cleveland Gear Company Process of continuous metal coating
US4594266A (en) * 1983-07-14 1986-06-10 Cockerill Sambre S.A. Process and an apparatus for baking an organic coating which has been applied to a substrate
US5041312A (en) * 1990-02-13 1991-08-20 Swartz Leroy Apparatus and method for coating a metal strip
US5768799A (en) * 1995-05-23 1998-06-23 Stein Heurtey Process and apparatus for coating metal sheets
US5895599A (en) * 1996-08-02 1999-04-20 Selas S.A. Induction heating device and continuous treatment installation including same

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012163334A1 (en) * 2011-05-27 2012-12-06 Thermprotec Gmbh Method and assembly for producing a coated metal strip

Also Published As

Publication number Publication date
FR2846261A1 (en) 2004-04-30
FR2846261B1 (en) 2005-01-21

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