EP0059136B1 - Process for coating metallic substrates with plastic materials and metal-plastic complexes thus obtained - Google Patents

Process for coating metallic substrates with plastic materials and metal-plastic complexes thus obtained Download PDF

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Publication number
EP0059136B1
EP0059136B1 EP19820400214 EP82400214A EP0059136B1 EP 0059136 B1 EP0059136 B1 EP 0059136B1 EP 19820400214 EP19820400214 EP 19820400214 EP 82400214 A EP82400214 A EP 82400214A EP 0059136 B1 EP0059136 B1 EP 0059136B1
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EP
European Patent Office
Prior art keywords
polyamide
process according
layer
primary layer
metal
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Expired
Application number
EP19820400214
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German (de)
French (fr)
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EP0059136A2 (en
EP0059136A3 (en
Inventor
Simon Ralph Kabalo
Franco Marchese
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ATO Chimie SA
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ATO Chimie SA
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Publication of EP0059136A3 publication Critical patent/EP0059136A3/en
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    • 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
    • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
    • B05D7/50—Multilayers
    • B05D7/52—Two layers
    • B05D7/53—Base coat plus clear coat type
    • B05D7/536—Base coat plus clear coat type each layer being cured, at least partially, separately
    • 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
    • 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
    • B05D2252/10—Applying the material on both sides
    • 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
    • B05D2451/00—Type of carrier, type of coating (Multilayers)
    • 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
    • B05D2504/00—Epoxy 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
    • B05D2505/00—Polyamides

Definitions

  • the invention relates to the field of coating of metallic substrates. More particularly, it relates to a process for coating metallic substrates using plastics making it possible to produce multi-layer metal-plastic complexes. It also relates to the products obtained by such a process.
  • the metals constituting the sheet were generally steel or galvanized steel or aluminum or an aluminum-based alloy.
  • the plastics used were mainly polyvinyl chloride, and to a lesser extent polyethylene.
  • the present invention relates to the application to a metal substrate of one or more layers of plastics, the outer layer always being polyamide.
  • the object of the present invention is on the one hand to provide a more economical method than the known methods which start from films produced beforehand, and on the other hand, to provide a method applicable to polyamides.
  • polyamides are indeed particularly advantageous by their resistance to temperature, abrasion, to chemical agents, which are better than those of plastics used until now, such as PVC and provide total protection against corrosion to the metal substrate. basic.
  • Patent FR-A-2075 916 describes a process for coating a metallic substrate, more specifically for the interior coating of aluminum walls of kegs intended to contain beer. After applying a primer, a polyamide powder is deposited electrostatically, the outer layer of polyamide is then melted. The polyamide layer obtained has a thickness of 125 to 175 microns.
  • the patent FR-A-2 075 916 does not propose a continuous coating process making it possible to achieve in a single pass an external coating of thin polyamide, due to the fact that it is limited to the implementation of a technique for electrostatically applying the polyamide powder.
  • the subject of the invention is a process which makes it possible in particular to continuously coat metallic substrates presented in strips, by virtue of the use of a dispersion of polyamide powder in an organic liquid phase, this powder having a determined particle size.
  • the subject of the invention is a method for coating a metal substrate, in particular for producing an anti-corrosion coating, according to which a primary layer and at least one layer of plastic are applied to said substrate, the primary layer containing a resin chosen from epoxyphenolic resins, mixtures of epoxy resins and phenolic resins and combinations of said resins and mixtures of resins, while the last layer of plastic material is a layer of polyamide, after which the whole is heated to melting the outer polyamide layer, said method being characterized in that said polyamide layer is continuously applied in the form of a suspension, in an organic liquid phase, of polyamide powder whose particle size is less than 40 microns , the thickness of the outer polyamide layer being between 20 and 50 microns, the process being carried out continuously and in a single pass.
  • the invention involves the application to the substrate of an organic bonding primer, susceptible to a modification of structure by heat.
  • the metal substrate intended to be covered with polyamide suspension is previously coated with a primer, because, among other functions, this ensures the connection between the metal and the polyamide coating, due to the fact the very good adhesiveness which it has both towards metals and polyamides.
  • the primer strengthens the metal protection provided by the polyamide coating firstly by preventing the path between metal and polyamide of gases such as oxygen, carbon dioxide, water vapor, and then, by superimposing its own protective action to that of polyamide.
  • the presence of the primer is even more essential when the sheet to be coated has not undergone a preparation treatment.
  • the primer contains an epoxy resin in an amount between 1 and 20% of the total weight of the primer, associated with a phenolic resin in an amount between 1 and 20% of the total weight of the primer, or an epoxy resin -phenolic in an amount between 1% and 20% of the total weight of the primary or a mixture of the above resins in the same weight proportions relative to the primary as those mentioned above.
  • the anti-corrosion action provided by the primer can be reinforced by adding to the primer corrosion-inhibiting chemical compounds such as zinc phosphate, zinc tetrahydroxychromate, strontium chromate, these salts which can be used alone or as a mixture.
  • the primer corrosion-inhibiting chemical compounds such as zinc phosphate, zinc tetrahydroxychromate, strontium chromate, these salts which can be used alone or as a mixture.
  • the second step of the coating process consists in coating the primer with a suspension of a thermoplastic fine powder based on polyamide, presented in a solvent or mixture of organic solvents.
  • the final step of heating the entire coating can allow proper attachment of the primer on the substrate.
  • the final heating step causes the polyamide particles to melt and forms a continuous and smooth layer on the substrate.
  • this is a purely physical transformation carried out under the effect of the rise in temperature, for example in a heat treatment oven. This characteristic is advantageous and constitutes an important difference with the processes of the prior art in which the heat treatment was intended to effect a chemical transformation comparable to a crosslinking in the final plastic layer.
  • the final layer or finishing layer is obtained by evaporation of the liquid phase in which the polyamide particles are suspended and by fusion of said particles to form the final layer.
  • the grain size of the polyamide powder corresponds to a specific particle size, being in a range less than 40 ⁇ and preferably between 10 to 40 ⁇ , particularly between 10 and 30 ⁇ .
  • the powders suspended are powders of polyamides, that is to say resins of high molecular weight obtained from lactams or amino acids whose hydrocarbon chain has a number of carbon atoms between 4 and 20 such as, for example, caprolactam, oenantholactam, dodecalactam, undecanolactam, dodecanolactam, 11 amino-undecanoic acid, 12 amino-dodecanoic acid.
  • the polyamide may also be a condensation product of a dicarboxylic acid with a diamine such as, for example, the polyamides 6.6, 6.9, 6.10, 6.12, 9.6, condensation products of hexamethylene diamine with adipic acid, the azelaic acid, sebacic acid, 1.12 dodecanedioic acid and nonamethylene diamine with adipic acid.
  • the powders can consist of copolyamides resulting from the polymerization of the various monomers mentioned above.
  • copolyamides result from the polycondensation of e-caprolactam, amino-undecanoic acid and / or lauryl lactam.
  • their melt viscosity is all the higher, which affects their spreading on the substrate during fusion; according to the present invention, the suspension may contain adjuvants which promote spreading of the molten polyamide despite a high melting viscosity.
  • the lower the molecular weight the more the coating will be fluid in the molten state to the detriment of its mechanical properties, its aging and its resistance to weathering.
  • the inherent viscosity (measured at 20 ° C. for a solution of 0.5 g in 100 ml of metacresol) of the polyamide powders, reflecting their molecular mass, is between the values 0.75 and 1.40; the nature of the polyamide and the final application of the coated substrate are the determining factors for choosing the most favorable value.
  • the polyamide powders used according to the invention can be obtained by all kinds of techniques known to a person skilled in the art, for example by grinding polyamide granules previously cooled with liquid nitrogen, or dissolving these granules in solvents hot and precipitation by cooling, among others.
  • the organic liquid phase containing the polyamide powder in suspension, comprises a solvent or mixture of solvents chosen from alcohols, esters, aromatic hydrocarbons, and ketones.
  • solvents examples include benzyl alcohol, N-methyl pyrrolidone, ethylglycol acetate, dibutylglycol acetate or mixtures of solvents marketed under the name Solvesso 100 and 150.
  • the suspension based on polyamide powder may contain various additives which promote suspension, such as expanded silica (for example the product known as Aerosil) or which modify the surface tension, as is known to man of the art. art in the field of paints and varnishes.
  • expanded silica for example the product known as Aerosil
  • surface tension as is known to man of the art. art in the field of paints and varnishes.
  • These powders can be in their natural state and, consequently, generate colorless or pigmented coatings, the pigment or pigments which can be introduced into the suspension by means of a cutting resin as is known to those skilled in the art. art for the formulation of pigmented compositions.
  • the coating can be done on one or both sides of such a sheet.
  • the method is applicable with the most advantages to metal strips of thickness between 0.2 mm and 2 mm approximately.
  • the thickness of the external polyamide finishing layer is between approximately 20 and 50 ⁇ .
  • the strip unwinding station includes a coil 1 and an accumulator allowing it to dampen the variations in length and voltage following the changes of coils.
  • the strip then passes through a primary coating station 3.
  • the station 3 includes a duo of cylinders working according to the known technique called "reverse roll •.
  • An alternative embodiment of this primary coating step is shown in Figure 2.
  • the solution to be applied is contained in a tank 10 and deposited on the strip by a duo of cylinders 11, 12.
  • a final thickness of 6 to 7 microns is considered sufficient for the primer.
  • the general reference 4 designates a drying and crosslinking oven for the primer deposited at station 3.
  • the temperature to be reached in the oven 4 will obviously depend on the nature of the primer.
  • peak metal temperature a measure of the true baking temperature of the primary.
  • the installation shown in FIG. 1 for implementing the method of the invention then comprises a station 5 for cooling by forced air of the strip coated with primer.
  • Station 6 is used to apply a thin polyamide powder dispersion layer according to the invention to the strip already coated with primer.
  • station 6 comprises a duo of cylinders working according to the principle of rotogravure (similar to FIG. 2).
  • a drying and gelling oven 7 is used to remove solvents from the organic phase and to melt the grains of fine powder into a continuous layer. On leaving the oven 7 the strip passes through a cooling station 8 and then into a reel 9 preceded by its accumulator 9a.
  • the temperature conditions in the oven 7 will depend on the nature of the polyamides used.
  • the area between the temperature curve recorded on the sheet between the entry and exit of the oven, the x-axis (indifferently graduated in space or time) and the two verticals corresponding to the entry and to leaving the oven corresponds to the energy used to carry out the operations for removing the solvents, crosslinking the cutting binder and melting the polyamide powder.
  • the method of the invention makes it possible to treat metallic substrates presented in coils, by means of a continuous fabrication line of the kind represented in FIG. 1.
  • This primer is characterized by a total absence of yellowing and good flexibility due to the presence of polyester; on the other hand, its resistance to boiling water is poor.
  • This primer is also characterized by an absence of yellowing.
  • This primer is characterized by good resistance to boiling water. It can therefore be seen that the formulation of the primer can be adapted to the end use of the coated sheet.
  • the polyamide powder can, depending on the desired applications, have a concentration in the dispersion varying from 20 to 50%.
  • It also serves as a cutting resin, a vector for various additives or a complement of fillers allowing the finishing coat to be tinted.
  • a mild steel strip in a continuous strip 0.7 mm thick having undergone a surface preparation for the dual purpose of protecting against corrosion and promoting adhesion with the commercial product referenced BONDERITE 914 of the Company PARKER, is introduced at station 3 for primary coating with a speed of approximately 30 m / mm.
  • the multilayered metalloplastic complex obtained can undergo successfully without exhibiting the phenomenon of detachment of the plastic coating the immersion test for 1000 hours in boiling water on test pieces having undergone cross-shaped notches in the coating.
  • a 0.5 mm thick strip of aluminum strip having undergone a surface preparation with the commercial product referenced COLARDIN 6204 from the company CFPL, receives at the coating station 3 a primary layer according to formula II d '' dry thickness of 4 to 5 microns and reaches a PMT of 249 ° C in the oven 4. Likewise, in the second oven 7, the strip also reaches a PMT of 249 ° C. after application of a layer of formula VI where the polyamide is a polyamide 12 of which it will retain a dry thickness of 25 microns.

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
  • Laminated Bodies (AREA)
  • Paints Or Removers (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)

Description

L'invention concerne le domaine de l'enduction de substrats métalliques. Elle a plus particulièrement pour objet un procédé pour l'enduction de substrats métalliques à l'aide de matières plastiques permettant de réaliser des complexes multi-couches métal-plastique. Elle a également pour objet les produits obtenus par un tel procédé.The invention relates to the field of coating of metallic substrates. More particularly, it relates to a process for coating metallic substrates using plastics making it possible to produce multi-layer metal-plastic complexes. It also relates to the products obtained by such a process.

A des fins décoratives ou de protection contre la corrosion, l'industrie a été amenée à réaliser des complexes multicouches métal-platique. Les procédés employés consistaient dans le collage d'une feuille plastique sur un feuillard approvisionné en continu à partir d'une bobine, ou dans le laminage à chaud, sur calandre ou laminoir, d'une tôle préalablement traitée par l'application d'un primaire d'adhérence.For decorative or corrosion protection purposes, the industry has had to produce metal-plastic multilayer complexes. The processes used consisted of gluing a plastic sheet on a strip supplied continuously from a reel, or in hot rolling, on a calender or rolling mill, of a sheet previously treated by the application of a adhesion primer.

Les métaux constituant la tôle étaient en général l'acier ou l'acier galvanisé ou encore l'aluminium ou un alliage à base d'aluminium.The metals constituting the sheet were generally steel or galvanized steel or aluminum or an aluminum-based alloy.

Les plastiques employés étaient principalement le polychlorure de vinyle, et dans une moindre mesure, le polyéthylène.The plastics used were mainly polyvinyl chloride, and to a lesser extent polyethylene.

La présente invention est relative à l'application sur un substrat métallique d'une ou plusieurs couches de matières plastiques, la couche externe étant toujours polyamidique.The present invention relates to the application to a metal substrate of one or more layers of plastics, the outer layer always being polyamide.

L'objet de la présente invention est d'une part de fournir un procédé plus économique que les procédés connus qui partent de films réalisés au préalable, et d'autre part, de fournir un procédé applicable aux polyamides.The object of the present invention is on the one hand to provide a more economical method than the known methods which start from films produced beforehand, and on the other hand, to provide a method applicable to polyamides.

Ces polyamides sont en effet particulièrement intéressants par leurs résistances à la température, à l'abrasion, aux agents chimiques, qui sont meilleures que celles des plastiques employés jusqu'ici, tels que le PVC et fournissent une protection totale contre la corrosion au substrat métallique de base.These polyamides are indeed particularly advantageous by their resistance to temperature, abrasion, to chemical agents, which are better than those of plastics used until now, such as PVC and provide total protection against corrosion to the metal substrate. basic.

Le brevet FR-A-2075 916 décrit un procédé pour l'enduction de substrat métallique, plus spécialement pour le revêtement intérieur des parois en aluminium de tonnelets destinés à contenir de la bière. Après application d'un primaire, on dépose une poudre de polyamide par voie électrostatique, la couche externe de polyamide est ensuite fondue. La couche de polyamide obtenue présente une épaisseur de 125 à 175 microns. Le brevet FR-A-2 075 916 ne propose pas un procédé continu d'enduction permettant d'aboutir en une seule passe à un revêtement externe de polyamide de faible épaisseur, en raison du fait qu'il est limité à la mise en oeuvre d'une technique d'application par voie électrostatique de la poudre de polyamide.Patent FR-A-2075 916 describes a process for coating a metallic substrate, more specifically for the interior coating of aluminum walls of kegs intended to contain beer. After applying a primer, a polyamide powder is deposited electrostatically, the outer layer of polyamide is then melted. The polyamide layer obtained has a thickness of 125 to 175 microns. The patent FR-A-2 075 916 does not propose a continuous coating process making it possible to achieve in a single pass an external coating of thin polyamide, due to the fact that it is limited to the implementation of a technique for electrostatically applying the polyamide powder.

L'invention a pour objet un procédé permettant notamment de revêtir en continu des substrats métalliques présentés en bandes, grâce à l'utilisation d'une dispersion de poudre de polyamide dans une phase liquide organique, cette poudre ayant une taille de particules déterminée.The subject of the invention is a process which makes it possible in particular to continuously coat metallic substrates presented in strips, by virtue of the use of a dispersion of polyamide powder in an organic liquid phase, this powder having a determined particle size.

L'invention a pour objet un procédé pour l'enduction d'un substrat métallique, notamment pour réaliser un revêtement anti-corrosion, selon lequel on applique sur ledit substrat une couche primaire et au moins une couche de matière plastique, la couche primaire contenant une résine choisie parmi les résines époxyphénoliques, les mélanges de résines époxy et de résines phénoliques et les combinaisons desdites résines et mélanges de résines, tandis que la dernière couche de matière plastique est une couche de polyamide, après quoi on chauffe l'ensemble jusqu'à fusion de la couche externe de polyamide, ledit procédé étant caractérisé en ce qu'on applique en continu ladite couche de polyamide sous forme de suspension, dans une phase liquide organique, de poudre de polyamide dont la taille de particules est inférieure à 40 microns, l'épaisseur de la couche externe de polyamide étant comprise entre 20 et 50 microns, le procédé étant réalisé en continu et en une seule passe.The subject of the invention is a method for coating a metal substrate, in particular for producing an anti-corrosion coating, according to which a primary layer and at least one layer of plastic are applied to said substrate, the primary layer containing a resin chosen from epoxyphenolic resins, mixtures of epoxy resins and phenolic resins and combinations of said resins and mixtures of resins, while the last layer of plastic material is a layer of polyamide, after which the whole is heated to melting the outer polyamide layer, said method being characterized in that said polyamide layer is continuously applied in the form of a suspension, in an organic liquid phase, of polyamide powder whose particle size is less than 40 microns , the thickness of the outer polyamide layer being between 20 and 50 microns, the process being carried out continuously and in a single pass.

Les caractéristiques avantageuses de l'invention sont obtenues par la combinaison du choix du primaire et de la couche externe de matière plastique, laquelle est appliquée sous forme d'une suspension de polyamide.The advantageous characteristics of the invention are obtained by the combination of the choice of primer and of the external layer of plastic material, which is applied in the form of a polyamide suspension.

L'invention comporte l'application sur le substrat d'un primaire organique d'accrochage, susceptible d'une modification de structure par la chaleur.The invention involves the application to the substrate of an organic bonding primer, susceptible to a modification of structure by heat.

En effet, il est indispensable que le substrat métallique destiné à être recouvert de suspension de polyamide soit préalablement enduit d'un primaire, parce que, entre autres fonctions, celui-ci assure la liaison entre le métal et le revêtement de polyamide, du fait de la très bonne adhésivité qu'il possède à la fois vis-à-vis des métaux et des polyamides.Indeed, it is essential that the metal substrate intended to be covered with polyamide suspension is previously coated with a primer, because, among other functions, this ensures the connection between the metal and the polyamide coating, due to the fact the very good adhesiveness which it has both towards metals and polyamides.

Le primaire renforce la protection du métal apportée par le revêtement polyamidique tout d'abord en empêchant le cheminement entre métal et polyamide des gaz tels que l'oxygène, le gaz carbonique, la vapeur d'eau, et ensuite, en venant superposer sa propre action de protection à celle du polyamide.The primer strengthens the metal protection provided by the polyamide coating firstly by preventing the path between metal and polyamide of gases such as oxygen, carbon dioxide, water vapor, and then, by superimposing its own protective action to that of polyamide.

Les causes de corrosion sont multiples et différentes suivant l'application de l'article métallique enduit ; on peut par exemple citer, entre autres :

  • - l'eau bouillante et les détergents dans le cas des machines à laver le linge ou la vaisselle,
  • - des agents chimiques divers si les tôles servent à construire des cuves de stockage de ces produits,
  • - les intempéries si les objets revêtus sont utilisés au dehors.
The causes of corrosion are multiple and different depending on the application of the coated metallic article; we can for example cite, among others:
  • - boiling water and detergents in the case of washing machines or dishes,
  • - various chemical agents if the sheets are used to build storage tanks for these products,
  • - bad weather if the coated objects are used outside.

La présence du primaire est encore plus indispensable lorsque la tôle à revêtir n'a pas subi de traitement de préparation.The presence of the primer is even more essential when the sheet to be coated has not undergone a preparation treatment.

Selon la présente invention, le primaire contient une résine époxy en une quantité comprise entre 1 et 20 % du poids total du primaire, associée à une résine phénolique en une quantité comprise entre 1 et 20 % du poids total du primaire, ou une résine époxy-phénolique en une quantité comprise entre 1 % et 20 % du poids total du primaire ou un mélange des résines ci-dessus dans les mêmes proportions pondérales par rapport au primaire que celles sus-mentionnées.According to the present invention, the primer contains an epoxy resin in an amount between 1 and 20% of the total weight of the primer, associated with a phenolic resin in an amount between 1 and 20% of the total weight of the primer, or an epoxy resin -phenolic in an amount between 1% and 20% of the total weight of the primary or a mixture of the above resins in the same weight proportions relative to the primary as those mentioned above.

Selon l'invention, l'action anti-corrosion procurée par le primaire peut être renforcée en ajoutant au primaire des composés chimiques inhibiteurs de corrosion tels que le phosphate de zinc, le tétrahydroxychromate de zinc, le chromate de strontium, ces sels pouvant être utilisés seuls ou en mélange.According to the invention, the anti-corrosion action provided by the primer can be reinforced by adding to the primer corrosion-inhibiting chemical compounds such as zinc phosphate, zinc tetrahydroxychromate, strontium chromate, these salts which can be used alone or as a mixture.

Dans une forme préférée de réalisation, la composition du primaire selon l'invention comprend un ou plusieurs des composés appartenant aux

  • - polyesters linéaires thermoplastiques de PF compris entre 100 et 150 °C, solubles dans le mélange de solvants utilisés, dont la teneur est comprise de préférence entre 10 et 25 % du poids total du primaire,
  • - isocyanates aliphatiques ou aromatiques bloqués et libérables à partir d'une température de 120 °C et dont la teneur est comprise entre 1 à 6 % du poids total du primaire,
  • - un sel minéral inhibiteur de corrosion appartenant au groupe constitué par le phosphate de zinc, le tétrahydroxychromate de zinc, le chromate de strontium, utilisés seuls ou en mélange, la teneur totale étant comprise entre 0,5 et 15 % du poids du primaire.
In a preferred embodiment, the composition of the primer according to the invention comprises one or more of the compounds belonging to the
  • - linear thermoplastic polyesters of PF of between 100 and 150 ° C, soluble in the mixture of solvents used, the content of which is preferably between 10 and 25% of the total weight of the primer,
  • - aliphatic or aromatic isocyanates blocked and releasable from a temperature of 120 ° C and whose content is between 1 to 6% of the total weight of the primer,
  • - a corrosion inhibiting mineral salt belonging to the group consisting of zinc phosphate, zinc tetrahydroxychromate, strontium chromate, used alone or as a mixture, the total content being between 0.5 and 15% of the weight of the primer.

La préparation de ces primaires s'effectue sans difficultés dans les appareils de mélange habituels, par exemple ceux pour peintùres ; il est recommandé d'utiliser des agitateurs disperseurs munis de turbines à dents périphériques particulièrement adaptés aux dispersions et aux empâtages ; il est bon d'empâter préalablement les additifs solides (silice, sels minéraux) ou insolubles dans une petite partie des solvants et d'ajouter la pâte obtenue au reste de la composition.The preparation of these primers is carried out without difficulty in the usual mixing devices, for example those for painters; it is recommended to use dispersing agitators fitted with turbines with peripheral teeth which are particularly suitable for dispersions and mashings; it is good to paste the solid additives (silica, mineral salts) or insoluble in a small part of the solvents beforehand and to add the paste obtained to the rest of the composition.

Ces techniques de formulation sont à la portée de l'homme de l'art et n'ont donc pas besoin d'être décrites plus en détail.These formulation techniques are within the reach of ordinary skill in the art and therefore need not be described in more detail.

Selon l'invention, la deuxième étape du procédé d'enduction consiste à revêtir le primaire d'une suspension d'une poudre fine thermoplastique à base de polyamide, présentée dans un solvant ou mélange de solvants organiques.According to the invention, the second step of the coating process consists in coating the primer with a suspension of a thermoplastic fine powder based on polyamide, presented in a solvent or mixture of organic solvents.

Après l'enduction du substrat métallique à l'aide du primaire, il est en général plus avantageux de sécher celui-ci avant d'appliquer la suspension de polyamide. Cette étape n'est toutefois pas indispensable dans la mesure où l'étape finale de chauffage de l'ensemble du revêtement peut permettre un accrochage convenable du primaire sur le substrat. L'étape de chauffage finale provoque la fusion des particules de polyamide et forme sur le substrat une couche continue et lisse. Il s'agit dans la couche de polyamide d'une transformation purement physique réalisée sous l'effet de l'élévation de température, par exemple dans un four de traitement thermique. Cette caractéristique est avantageuse et constitue une différence importante avec les procédés de la technique antérieure dans lesquels le traitement thermique avait pour but d'opérer une transformation chimique assimilable à une réticulation dans la couche de matière plastique finale.After coating the metal substrate with the primer, it is generally more advantageous to dry it before applying the polyamide suspension. This step is however not essential insofar as the final step of heating the entire coating can allow proper attachment of the primer on the substrate. The final heating step causes the polyamide particles to melt and forms a continuous and smooth layer on the substrate. In the polyamide layer, this is a purely physical transformation carried out under the effect of the rise in temperature, for example in a heat treatment oven. This characteristic is advantageous and constitutes an important difference with the processes of the prior art in which the heat treatment was intended to effect a chemical transformation comparable to a crosslinking in the final plastic layer.

Au contraire, dans l'invention, la couche terminale ou couche de finition est obtenue par évaporation de la phase liquide dans laquelle se trouvent suspendues les particules de polyamide et par fusion desdites particules pour former la couche définitive.On the contrary, in the invention, the final layer or finishing layer is obtained by evaporation of the liquid phase in which the polyamide particles are suspended and by fusion of said particles to form the final layer.

Selon une caractéristique essentielle de l'invention, la taille des grains de la poudre de polyamide correspond à une granulométrie spécifique, se situant dans une gamme inférieure à 40 µ et de préférence comprise entre 10 à 40 µ, particulièrement entre 10 et 30 µ.According to an essential characteristic of the invention, the grain size of the polyamide powder corresponds to a specific particle size, being in a range less than 40 μ and preferably between 10 to 40 μ, particularly between 10 and 30 μ.

Les poudres mises en suspension sont des poudres de polyamides, c'est-à-dire de résines de haut poids moléculaire obtenues à partir de lactames ou d'aminoacides dont la chaîne hydrocarbonée possède un nombre d'atomes de carbone compris entre 4 et 20 comme, par exemple, le caprolactame, l'oenantholactame, le dodécalactame, l'undécanolactame, le dodécanolactame, l'acide 11 amino-undécanoïque, l'acide 12 amino-dodécanoïque.The powders suspended are powders of polyamides, that is to say resins of high molecular weight obtained from lactams or amino acids whose hydrocarbon chain has a number of carbon atoms between 4 and 20 such as, for example, caprolactam, oenantholactam, dodecalactam, undecanolactam, dodecanolactam, 11 amino-undecanoic acid, 12 amino-dodecanoic acid.

Le polyamide peut également être un produit de condensation d'un acide dicarboxylique avec une diamine comme, par exemple, les polyamides 6.6, 6.9, 6.10, 6.12, 9.6, produits de condensation de l'hexaméthylène diamine avec l'acide adipique, l'acide azélaïque, l'acide sébacique, l'acide 1.12 dodécanedioïque et de la nonaméthylène diamine avec l'acide adipique.The polyamide may also be a condensation product of a dicarboxylic acid with a diamine such as, for example, the polyamides 6.6, 6.9, 6.10, 6.12, 9.6, condensation products of hexamethylene diamine with adipic acid, the azelaic acid, sebacic acid, 1.12 dodecanedioic acid and nonamethylene diamine with adipic acid.

Bien entendu, les poudres peuvent être constituées de copolyamides résultant de la polymérisation des divers monomères cités ci-dessus.Of course, the powders can consist of copolyamides resulting from the polymerization of the various monomers mentioned above.

Conviennent particulièrement bien pour la mise en oeuvre du procédé les poudres de :

  • Polyamide 6, obtenues par polymérisation de l'e-caprolactame
  • Polyamide 11, obtenues par polycondensation de l'acide 11 amino-undécanoïque
  • Polyamide 12, obtenues par polycondensation de l'acide 12 amino-dodécanoïque ou du dodécanolactame

ou des copolyamides obtenus par la polymérisation de deux ou de trois des monomères cités ci-dessus.Particularly suitable for implementing the process are powders of:
  • Polyamide 6, obtained by polymerization of e-caprolactam
  • Polyamide 11, obtained by polycondensation of amino-undecanoic acid 11
  • Polyamide 12, obtained by polycondensation of amino-dodecanoic acid 12 or dodecanolactam

or copolyamides obtained by the polymerization of two or three of the monomers mentioned above.

Des copolyamides intéressants résultent de la polycondensation de l'e-caprolactame, de l'acide amino-undécanoïque et/ou du lauryl lactame.Interesting copolyamides result from the polycondensation of e-caprolactam, amino-undecanoic acid and / or lauryl lactam.

Plus le poids moléculaire des polyamides constitutifs des poudres est élevé et meilleures sont leur résistance au vieillissement et leurs propriétés mécaniques. Par contre, leur viscosité de fusion est d'autant plus élevée, ce qui nuit à leur étalement sur le substrat lors de la fusion ; selon la présente invention la suspension peut contenir des adjuvants favorisant l'étalement du polyamide fondu malgré une viscosité de fusion élevée. Inversement, plus le poids moléculaire est faible et plus le revêtement sera fluide à l'état fondu au détriment de ses propriétés mécaniques, de son vieillissement et de sa résistance aux intempéries.The higher the molecular weight of the polyamides constituting the powders, the better their resistance to aging and their mechanical properties. However, their melt viscosity is all the higher, which affects their spreading on the substrate during fusion; according to the present invention, the suspension may contain adjuvants which promote spreading of the molten polyamide despite a high melting viscosity. Conversely, the lower the molecular weight, the more the coating will be fluid in the molten state to the detriment of its mechanical properties, its aging and its resistance to weathering.

En général, la viscosité inhérente (mesurée à 20 °C pour une solution de 0,5 g dans 100 ml de métacrésol) des poudres de polyamides, reflet de leur masse moléculaire, est comprise entre les valeurs 0,75 et 1,40 ; la nature du polyamide et l'application finale du substrat revêtu sont les facteurs déterminants pour choisir la valeur la plus favorable.In general, the inherent viscosity (measured at 20 ° C. for a solution of 0.5 g in 100 ml of metacresol) of the polyamide powders, reflecting their molecular mass, is between the values 0.75 and 1.40; the nature of the polyamide and the final application of the coated substrate are the determining factors for choosing the most favorable value.

Les poudres de polyamides utilisées selon l'invention peuvent être obtenues par toutes sortes de techniques connues de l'homme de l'art, par exemple par broyage de granulés de polyamides préalablement refroidis par de l'azote liquide, ou dissolution de ces granulés dans des solvants à chaud et précipitation par refroidissement, entre autres.The polyamide powders used according to the invention can be obtained by all kinds of techniques known to a person skilled in the art, for example by grinding polyamide granules previously cooled with liquid nitrogen, or dissolving these granules in solvents hot and precipitation by cooling, among others.

Les procédés par polymérisation anionique du ou des monomères dans des solvants, dans lesquels les polymères se séparent sous forme de poudres du milieu réactionnel dans lequel ils sont devenus insolubles, sont recommandés et, plus particulièrement, ceux décrits dans les brevets FR-1 601 194, 1 601 195 et 1 602 751 ; en effet, les particules constituant la poudre sont de petites sphères particulièrement aptes à donner de bonnes suspensions et des revêtements réguliers après fusion sur la tôle.The processes by anionic polymerization of the monomer (s) in solvents, in which the polymers separate in the form of powders from the reaction medium in which they have become insoluble, are recommended and, more particularly, those described in patents FR-1 601 194 , 1,601,195 and 1,602,751; in fact, the particles constituting the powder are small spheres particularly suitable for giving good suspensions and regular coatings after melting on the sheet.

La phase liquide organique, contenant la poudre de polyamide en suspension, comprend un solvant ou mélange de solvants choisis parmi les alcools, les esters, les hydrocarbures aromatiques, et les cétones.The organic liquid phase, containing the polyamide powder in suspension, comprises a solvent or mixture of solvents chosen from alcohols, esters, aromatic hydrocarbons, and ketones.

Des exemples spécifiques de tels solvants sont l'alcool benzylique, la N-méthyl pyrrolidone, l'acétate d'éthylglycol, l'acétate de dibutylglycol ou les mélanges de solvants mis sur le marché sous la dénomination Solvesso 100 et 150.Specific examples of such solvents are benzyl alcohol, N-methyl pyrrolidone, ethylglycol acetate, dibutylglycol acetate or mixtures of solvents marketed under the name Solvesso 100 and 150.

La suspension à base de poudre de polyamide peut contenir divers additifs favorisant la mise en suspension, tels que la silice expansée (par exemple le produit connu sous le nom Aerosil) ou modifiant la tension superficielle, comme cela est connu par l'homme de l'art dans le domaine des peintures et vernis.The suspension based on polyamide powder may contain various additives which promote suspension, such as expanded silica (for example the product known as Aerosil) or which modify the surface tension, as is known to man of the art. art in the field of paints and varnishes.

Ces poudres peuvent être à l'état naturel et, par suite, engendrer des revêtements incolores, ou pigmentés, le ou les pigments pouvant être introduits dans la suspension grâce à une résine de coupage ainsi qu'il est connu de l'homme de l'art en vue de la formulation des compositions pigmentées.These powders can be in their natural state and, consequently, generate colorless or pigmented coatings, the pigment or pigments which can be introduced into the suspension by means of a cutting resin as is known to those skilled in the art. art for the formulation of pigmented compositions.

Selon l'invention, il est possible d'enduire les substrats métalliques les plus variés, en particulier des tôles d'acier galvanisé, d'aluminium ou d'alliages à base d'aluminium. Il va sans dire que l'enduction peut se faire sur l'une ou les deux faces d'une telle tôle. Le procédé est applicable avec le plus d'avantages à des feuillards métalliques d'épaisseur comprise entre 0,2 mm et 2 mm environ. Dans ce cas, l'épaisseur de la couche externe polyamidique de finition est comprise entre 20 et 50 µ environ.According to the invention, it is possible to coat the most varied metallic substrates, in particular sheets of galvanized steel, aluminum or aluminum-based alloys. It goes without saying that the coating can be done on one or both sides of such a sheet. The method is applicable with the most advantages to metal strips of thickness between 0.2 mm and 2 mm approximately. In this case, the thickness of the external polyamide finishing layer is between approximately 20 and 50 μ.

Le procédé de l'invention sera maintenant illustré sans être aucunement limité par les exemples et la description ci-après, faites en référence aux dessins annexés sur lesquels :

  • Figure 1 illustre schématiquement un procédé d'enduction en continu d'un feuillard métallique.
  • Figure 2 représente une variante d'exécution de l'opération d'enduction primaire.
The process of the invention will now be illustrated without being in any way limited by the examples and the description below, made with reference to the appended drawings in which:
  • Figure 1 schematically illustrates a process for continuously coating a metal strip.
  • Figure 2 shows an alternative embodiment of the primary coating operation.

En se référant à la figure 1, on voit à la gauche de la figure le poste de déroulement du feuillard. Il comprend une bobine 1 et un accumulateur la permettant d'amortir les variations de longueur et de tension consécutives aux changements de bobines.Referring to Figure 1, we see to the left of the figure the strip unwinding station. It includes a coil 1 and an accumulator allowing it to dampen the variations in length and voltage following the changes of coils.

La référence 2 désigne schématiquement une installation de traitement de surface qui comprend en réalité plusieurs postes à savoir :

  • - dégraissage grossier
  • - brossage
  • - dégraissage fin
  • - rinçage à chaud
  • - phosphatation
  • - chromatation
  • - rinçage à froid
  • - rinçage chromique
Reference 2 schematically designates a surface treatment installation which actually comprises several stations, namely:
  • - coarse degreasing
  • - brushing
  • - fine degreasing
  • - hot rinse
  • - phosphating
  • - chromating
  • - cold rinse
  • - chromic rinsing

Ces postes consistent en des bacs différents où circule le feuillard.These stations consist of different trays where the strip circulates.

Le feuillard passe ensuite dans un poste 3 d'enduction de primaire. Dans l'exemple schématiquement représenté à la figure 1, le poste 3 comprend un duo de cylindres travaillant d'après la technique connue dite « reverse roll •. Une variante d'exécution de cette étape d'enduction de primaire est représentée à la figure 2. Celle-ci représente schématiquement une enduction par la technique dite de rotogravure. Dans ce cas la solution à appliquer est contenue dans un bac 10 et déposée sur le feuillard par un duo de cylindres 11, 12.The strip then passes through a primary coating station 3. In the example schematically shown in Figure 1, the station 3 includes a duo of cylinders working according to the known technique called "reverse roll •. An alternative embodiment of this primary coating step is shown in Figure 2. This schematically represents a coating by the technique called rotogravure. In this case the solution to be applied is contained in a tank 10 and deposited on the strip by a duo of cylinders 11, 12.

Il va sans dire que pour enduire les deux faces du feuillard il faut prévoir un autre poste d'enduction du même type.It goes without saying that to coat the two sides of the strip it is necessary to provide another coating station of the same type.

En général une épaisseur finale de 6 à 7 microns est considérée comme suffisante pour le primaire.In general, a final thickness of 6 to 7 microns is considered sufficient for the primer.

En se référant de nouveau à la figure 1 on a désigné par la référence générale 4 un four de séchage et de réticulation du primaire déposé au poste 3. La température à atteindre dans le four 4 dépendra évidemment de la nature du primaire.Referring again to FIG. 1, the general reference 4 designates a drying and crosslinking oven for the primer deposited at station 3. The temperature to be reached in the oven 4 will obviously depend on the nature of the primer.

Dans la pratique on se sert de la température atteinte par le métal du feuillard (dite pic métal température ou PMT) comme mesure de la température de cuisson vraie du primaire.In practice, we use the temperature reached by the metal of the strip (called peak metal temperature or PMT) as a measure of the true baking temperature of the primary.

L'installation représentée à la figure 1 pour la mise en oeuvre du procédé de l'invention comprend ensuite un poste de refroidissement 5 par air pulsé du feuillard enduit de primaire. Le poste 6 sert à appliquer sur le feuillard déjà enduit de primaire une couche de dispersion de poudre fine polyamidique selon l'invention. Dans l'exemple représenté le poste 6 comprend un duo de cylindres travaillant suivant le principe de la rotogravure (similaire à figure 2). Un four 7 de séchage et de gélification sert à évacuer des solvants de la phase organique et à fondre les grains de poudre fine pour en faire une couche continue. A sa sortie du four 7 le feuillard passe dans un poste refroidisseur 8 puis dans un enrouleur 9 précédé de son accumulateur 9a.The installation shown in FIG. 1 for implementing the method of the invention then comprises a station 5 for cooling by forced air of the strip coated with primer. Station 6 is used to apply a thin polyamide powder dispersion layer according to the invention to the strip already coated with primer. In the example shown, station 6 comprises a duo of cylinders working according to the principle of rotogravure (similar to FIG. 2). A drying and gelling oven 7 is used to remove solvents from the organic phase and to melt the grains of fine powder into a continuous layer. On leaving the oven 7 the strip passes through a cooling station 8 and then into a reel 9 preceded by its accumulator 9a.

Les conditions de température dans le four 7 dépendront de la nature des polyamides utilisés.The temperature conditions in the oven 7 will depend on the nature of the polyamides used.

On admet que l'aire comprise entre la courbe des températures enregistrée sur la tôle entre l'entrée et la sortie du four, l'axe des abscisses (gradué indifféremment en espace ou temps) et les deux verticales correspondant à l'entrée et à la sortie du four, correspond à l'énergie employée pour réaliser les opérations d'évacuation des solvants, réticulation du liant de coupage et fusion de la poudre polyamidique.We admit that the area between the temperature curve recorded on the sheet between the entry and exit of the oven, the x-axis (indifferently graduated in space or time) and the two verticals corresponding to the entry and to leaving the oven, corresponds to the energy used to carry out the operations for removing the solvents, crosslinking the cutting binder and melting the polyamide powder.

L'expérience a montré que suivant l'application envisagée, les propriétés recherchées et leur degré d'intensité, on pouvait faire varier les PMT ci-dessus dans l'intervalle 230° à 260 °C. Ces indications sont données à l'homme de l'art à titre purement illustratif et il va sans dire qu'on peut s'en écarter sans pour autant sortir du cadre de l'invention.Experience has shown that, depending on the application envisaged, the properties sought and their degree of intensity, the above PMTs can be varied in the range 230 ° to 260 ° C. These indications are given to a person skilled in the art for purely illustrative purposes and it goes without saying that one can deviate from them without going beyond the ambit of the invention.

On voit donc que le procédé de l'invention permet de traiter des substrats métalliques présentés en bobines, grâce à une ligne de fàbrication en continu du genre représenté à la figure 1.It can therefore be seen that the method of the invention makes it possible to treat metallic substrates presented in coils, by means of a continuous fabrication line of the kind represented in FIG. 1.

Dans les exemples purement illustratifs qui suivent, on a mis en oeuvre diverses formulations de primaire et de couches polyamidiques de finition. Dans ces exemples toutes les parties sont indiquées en poids, sauf indication contraire et les divers composants sont énumérés dans l'ordre de leur intervention et d'introduction au sein de la composition.

Figure imgb0001
In the purely illustrative examples which follow, various formulations of primer and of polyamide finishing layers have been used. In these examples, all the parts are indicated by weight, unless otherwise indicated and the various components are listed in the order of their intervention and introduction into the composition.
Figure imgb0001

Ce primaire se caractérise par une absence totale de jaunissement et une bonne souplesse due à la présence de polyester ; par contre, sa tenue à l'eau bouillante est médiocre.

Figure imgb0002
This primer is characterized by a total absence of yellowing and good flexibility due to the presence of polyester; on the other hand, its resistance to boiling water is poor.
Figure imgb0002

Ce primaire se caractérise également par une absence de jaunissement.

Figure imgb0003
This primer is also characterized by an absence of yellowing.
Figure imgb0003

Ce primaire se caractérise par une bonne tenue à l'eau bouillante. On voit donc que la formulation du primaire peut être adaptée à l'utilisation finale de la tôle revêtue.This primer is characterized by good resistance to boiling water. It can therefore be seen that the formulation of the primer can be adapted to the end use of the coated sheet.

C'est ainsi que les formules décrites dans les exemples I et Il seront recommandées pour leur absence de jaunissement. Ce dernier, dans certaines applications, n'est pas souhaitable car il arrive parfois que la sous-couche se laisse voir par transparence à travers le revêtement de polyamide. Par contre, leur tenue à l'eau bouillanté n'est pas très bonne.This is how the formulas described in Examples I and II will be recommended for their absence of yellowing. The latter, in certain applications, is not desirable because it sometimes happens that the undercoat is visible through transparency through the polyamide coating. However, their resistance to boiled water is not very good.

C'est l'inverse dans le cas du primaire de l'exemple III qui est jaune mais résiste très bien à l'eau très chaude : 75 °C.

Figure imgb0004
It is the opposite in the case of the primer of Example III which is yellow but very resistant to very hot water: 75 ° C.
Figure imgb0004

Dans ce même type de formule, on peut substituer à l'alcool benzylique les solvants suivants :

  • - isophorone
  • - acétate d'éthylglycol
  • - dibutylglycolacétate
In the same type of formula, the following solvents can be substituted for benzyl alcohol:
  • - isophorone
  • - ethyl glycol acetate
  • - dibutylglycolacetate

La poudre de polyamide peut, suivant les applications recherchées, avoir une concentration dans la dispersion variant de 20 à 50 %.The polyamide powder can, depending on the desired applications, have a concentration in the dispersion varying from 20 to 50%.

Formule V (polyamide)Formula V (polyamide)

Les composants étant, comme il a été dit précédemment pour le primaire, ajoutés dans l'ordre indiqué ci-dessous, la formule s'établit comme suit :

Figure imgb0005
Figure imgb0006
 The components being, as it was said previously for the primary, added in the order indicated below, the formula is established as follows:
Figure imgb0005
Figure imgb0006

Il sert également de résine de coupage, vecteur des additifs divers ou d'un complément de charges permettant la mise à la teinte de la couche de finition.It also serves as a cutting resin, a vector for various additives or a complement of fillers allowing the finishing coat to be tinted.

Exemple 1Example 1

Un feuillard d'acier doux en bande continue de 0,7 mm d'épaisseur, ayant subi une préparation de surface dans le double but de protection contre la corrosion et de promotion de l'adhérence avec le produit commercial référencé BONDERITE 914 de la Société PARKER, est introduit au poste 3 d'enduction de primaire avec une vitesse d'environ 30 m/mm.A mild steel strip in a continuous strip 0.7 mm thick, having undergone a surface preparation for the dual purpose of protecting against corrosion and promoting adhesion with the commercial product referenced BONDERITE 914 of the Company PARKER, is introduced at station 3 for primary coating with a speed of approximately 30 m / mm.

Il y reçoit une couche de primaire selon la formule III de 7 microns d'épaisseur à sec, et séjourne dans le four 4 pendant une durée d'environ 30 à 60 secondes et atteint un « Pic Métal Température (PMT) de 241 °C. Il passe dans le refroidissement 5 avant de se présenter à l'entrée du poste 6 d'enduction où il reçoit une couche de polyamide 11 selon formule IV d'épaisseur à sec de 30 microns. Dans le four 7, le feuillard atteint un PMT de 230 °C avant d'être refroidi et enroulé.It receives a layer of primer there according to formula III of 7 microns thick when dry, and remains in the oven 4 for a period of approximately 30 to 60 seconds and reaches a “Metal Peak Temperature (PMT) of 241 ° C. . It passes through the cooling 5 before being presented at the entrance to the coating station 6 where it receives a layer of polyamide 11 according to formula IV with a dry thickness of 30 microns. In the oven 7, the strip reaches a MTP of 230 ° C before being cooled and rolled up.

Le complexe mutlicouches métalloplastique obtenu peut subir avec succès sans présenter le phénomène de décollement du revêtement plastique le test d'immersion pendant 1 000 heures dans l'eau bouillante sur des éprouvettes ayant subi des entailles en forme de croix dans le revêtement.The multilayered metalloplastic complex obtained can undergo successfully without exhibiting the phenomenon of detachment of the plastic coating the immersion test for 1000 hours in boiling water on test pieces having undergone cross-shaped notches in the coating.

Exemple 2Example 2

Un feuillard d'aluminium en bande continue de 0,5 mm d'épaisseur, ayant subi une préparation de surface avec le produit commercial référencé COLARDIN 6204 de la Société C.F.P.L, reçoit au poste d'enduction 3 une couche primaire selon la formule Il d'épaisseur à sec de 4 à 5 microns et atteint dans le four 4 un PMT de 249 °C. De même, dans le deuxième four 7 le feuillard atteint aussi un PMT de 249 °C après application d'une couche de formule VI où le polyamide est un polyamide 12 dont il conservera une épaisseur à sec de 25 microns.A 0.5 mm thick strip of aluminum strip, having undergone a surface preparation with the commercial product referenced COLARDIN 6204 from the company CFPL, receives at the coating station 3 a primary layer according to formula II d '' dry thickness of 4 to 5 microns and reaches a PMT of 249 ° C in the oven 4. Likewise, in the second oven 7, the strip also reaches a PMT of 249 ° C. after application of a layer of formula VI where the polyamide is a polyamide 12 of which it will retain a dry thickness of 25 microns.

Claims (19)

1. Process for coating a metal substrate, particularly to produce an anticorrosion covering, according to which a primary layer and at least one layer of plastic are applied to the said substrate, the primary layer comprising a resin chosen from epoxyphenolic resins, mixtures of epoxy resins and phenolic resins and combinations of the said resins and mixtures of resins, while the last layer of plastic material is a layer of polyamide, after which the whole is heated until the outer layer of polyamide melts, the said process being characterised in that the said layer of polyamide is applied continuously in the form of a suspension, in an organic liquid phase, of polyamide powder the particle size of which is below 40 microns, the thickness of the outer layer of polyamide being between 20 and 50 microns, the process being carried out continuously and in a single step.
2. Process according to Claim 1, characterised in that the metal substrate is made of a ferrous alloy, steel, galvanised steel, aluminium or an aluminium alloy.
3. Process according to either of Claims 1 or 2, characterised in that metal sheets or strips, for example of a thickness between 0.2 mm and 2 mm, are treated.
4. Process according to any one of Claims 1 to 3, characterised in that, for the purpose of the application of the primary layer, the content of epoxyphenolic resin or expoxy resin associated with the phenolic resin is between 1 and 20 per cent of the total weight of the primary layer.
5. Process according to any one of Claims 1 to 4, characterised in that the primary layer contains an inorganic corrosion-inhibitor salt belonging to the group consisting of zinc phosphate, zinc tetrahyd- roxychromate and strontium chromate, which are employed alone or in a mixture, the total content being between 0.5 and 15 % of the weight of the primary layer.
6. Process according to any one of Claims 1 to 5, characterised in that the primary layer comprises one or more of the compounds belonging to
- thermoplastic linear polyesters with an M.P. of between 100 and 150 °C, which are soluble in the mixture of solvents employed, and the content of which is preferably between 10 and 25 % of the total weight of the primary layer
- aliphatic or aromatic blocked isocyanates which can be released starting at a temperature of 120°C and the content of which is between 1 and 6 % of the total weight of the primary layer.
7. Process according to any one of Claims 1 to 6, characterised in that the primary layer is dried and croslinked by heating, in particular between about 230 and 260 °C.
8. Process according to any one of Claims 1 to 7, characterised in that the particle size of the polyamide powder applied in the form of a suspension to the substrate which is coated with the primary layer is between 10 and 40 µ, in particular between 10 and 30 w.
9. Process according to any one of Claims 1 to 8, characterised in that the polyamide powders forming the suspensions are based on polyamides containing 4 to 20 carbon atoms in their hydrocarbon chain.
10. Process according to any one of Claims 1 to 8, characterised in that the polyamide powders are based on polyamides belonging to the group consisting of polyamide 6, polyamide 11, polyamide 12 or copolyamides 6/11, 6/12, 6/11/12 and 11/12.
11. Process according to any one of Claims 1 to 10, characterised in that the inherent viscosity (measured at 20 °C for a solution containing 0.5 g in 100 ml of meta-cresol) of the polyamide powders, reflecting their molecular weight, is between the values of 0.75 and 1.40.
12. Process according to any one of Claims 1 to 11, characterised in that the organic liquid phase containing the polyamide powder in suspension comprises a solvent or mixture of solvents which are chosen from alcohols, esters, aromatic hydrocarbons and ketones.
13. Process according to any one of Claims 1 to 12, characterised in that the polyamide powders are employed in the natural state or with the addition of one or more pigments, which may be introduced into the suspension by means of a blending resin.
14. Process according to any one of Claims 1 to 13, characterised in that the final heating producing the continuous outer polyamide layer by a purely physical conversion (melting of the polyamide particles) is a carried out between about 230 and 260 °C.
15. Process according to any one of Claims 1 to 14, characterised in that the thickness of the primary layer is of the order of 6 to 7 microns.
16. Process according to any one of Claims 1 to 15, characterised in that metal strips of a thickness between 0.2 mm and 2 mm are treated.
17. Process according to any one of Claims 1 to 16, characterised in that the organic liquid phase containing the polyamide powder in suspension comprises a solvent or mixture of solvents, to which there have been added one or more components belonging to the group consisting of :
- the product sold by the company American Cyanamid under the name of CYMEL 303 @ and which is a hexamethoxymethylmelamine
- the product marketed by the company Bayer under the name of SILICONE OL, which is a surface- active agent
- the product marketed by the company Esso under the name of SOLVESSO 150, which is an aromatic solvent containing 9 carbon atoms
- the products marketed by the company Rohm and Haas under the names of PARALOID B 48 and DM 54, the said products facilitating the wetting and the adhesion of the dispersion to the primary layers.
- the product marketed by the company Shell under the name of EPIKOTE 1001, which is a polycondensate of epichlorohydrin and diphenylolpropane.
18. Metal-plastic complexes produced by the process according to any one of Claims 1 to 17.
19. Metal-plastic complexes according to Claim 18, characterised in that they comprise a metal strip with a thickness of between 0.2 mm and 5 mm, a bonding primary layer and a continuous outer polyamide layer with a thickness of between 20 and 50 microns.
EP19820400214 1981-02-23 1982-02-05 Process for coating metallic substrates with plastic materials and metal-plastic complexes thus obtained Expired EP0059136B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8103528A FR2500371A1 (en) 1981-02-23 1981-02-23 PROCESS FOR THE CONTINUOUS PRODUCTION OF METAL-PLASTIC MULTILAYER COMPLEXES AND PRODUCTS OBTAINED
FR8103528 1981-02-23

Publications (3)

Publication Number Publication Date
EP0059136A2 EP0059136A2 (en) 1982-09-01
EP0059136A3 EP0059136A3 (en) 1982-10-06
EP0059136B1 true EP0059136B1 (en) 1985-09-18

Family

ID=9255518

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Application Number Title Priority Date Filing Date
EP19820400214 Expired EP0059136B1 (en) 1981-02-23 1982-02-05 Process for coating metallic substrates with plastic materials and metal-plastic complexes thus obtained

Country Status (5)

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EP (1) EP0059136B1 (en)
JP (1) JPS57156070A (en)
CA (1) CA1179558A (en)
DE (1) DE3266260D1 (en)
FR (1) FR2500371A1 (en)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61177237A (en) * 1985-02-02 1986-08-08 日新製鋼株式会社 Coated steel plate for muffler and manufacture thereof
JPS61177238A (en) * 1985-02-02 1986-08-08 日新製鋼株式会社 Coated steel plate for muffler and manufacture thereof
US5229214A (en) * 1989-07-31 1993-07-20 Akzo N.V. Preprimed metal substrates for formed metal applications
DE19933697A1 (en) * 1999-07-17 2001-01-18 Dieter Mueller Process for coating the surface of galvanized iron or steel workpieces
WO2009149143A1 (en) * 2008-06-03 2009-12-10 E. I. Du Pont De Nemours And Company Adhesion of polyamides to epoxy resins
CN103041966B (en) 2011-10-17 2014-12-24 宝山钢铁股份有限公司 Method for producing ultra-thick insulating coating on surface of electrical steel
JP6918973B2 (en) * 2017-12-13 2021-08-11 昭和電工株式会社 Composite laminate and its manufacturing method, and metal resin bonded body and its manufacturing method

Family Cites Families (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
LU37436A1 (en) * 1958-07-18
FR1215101A (en) * 1958-11-05 1960-04-14 Pechiney Process for coating metal surfaces with polyolefins
BE683230A (en) * 1966-06-27 1966-12-01
US3593848A (en) * 1968-02-26 1971-07-20 Atlas Coatings Corp Foam-covered coil and methods of manufacturing the same
FR1601195A (en) * 1968-12-31 1970-08-10
FR1602751A (en) * 1968-12-31 1971-01-25
FR1601194A (en) * 1968-12-31 1970-08-10
GB1322381A (en) * 1970-01-02 1973-07-04 British Aluminium Co Ltd Protective coated aluminium and a process for the application of a protective coating to aluminium
IT964886B (en) * 1971-08-24 1974-01-31 Cabot Corp POWDER COMPOSITION FOR SOLVENT-FREE COATING TECHNIQUES
JPS515018B2 (en) * 1972-05-18 1976-02-17
SE387133B (en) * 1972-10-18 1976-08-30 Diamond Shamrock Corp WAY TO PREPARE A BASIC TRANSFER COMPOSITION
JPS5758385B2 (en) * 1973-08-27 1982-12-09 Daicel Chem
GB2019252B (en) * 1978-04-03 1982-07-21 Oakland Corp Friction locking threaded fastener
JPS55152055A (en) * 1979-05-16 1980-11-27 Toa Gosei Chem Ind Resin coated zinc plated steel plate and adhering vessel using said resin coated zinc plated steel plate as blank

Also Published As

Publication number Publication date
FR2500371A1 (en) 1982-08-27
DE3266260D1 (en) 1985-10-24
FR2500371B1 (en) 1983-06-03
JPH0230308B2 (en) 1990-07-05
EP0059136A2 (en) 1982-09-01
EP0059136A3 (en) 1982-10-06
JPS57156070A (en) 1982-09-27
CA1179558A (en) 1984-12-18

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