EP2130951B1 - Method for producing a metal panel and resulting metal panel - Google Patents

Description

Current situation

1. 1) Le développement de nouveaux revêtements organiques transparents sur l'acier inoxydable, qui permettent de garder ses caractéristiques esthétiques ; qui protègent le matériau contre la corrosion; qui permettent l'utilisation d'aciers composés d'alliages plus faibles, de coûts moins élevés (de produits).
2. 2) Le développement de nouveaux revêtements organiques, à base de film qui imite le design de l'acier inoxydable, appliqués sur de l'acier à faible teneur en carbone, laminé à froid et galvanisé; qui permettent d'obtenir le même aspect et apportent une résistance adéquate contre la corrosion dans les secteurs cités.

The sharp increase in consumption of stainless steel in recent years, in various industries such as electrical appliances (fridges, dishwashers, ovens, microwaves, etc.), elevators, cold rooms in the hotel industry, and all types of decorative metal furniture, have caused a great increase in the price of this steel. This strong demand on the market, together with the search for new coatings, which protect stainless steel against stains and corrosion factors while taking care of its aesthetics, have led to a continuous development of new products that can be divided into two groups:

1. 1) The development of new transparent organic coatings on stainless steel, which allow to keep its aesthetic characteristics; that protect the material against corrosion; that allow the use of steels composed of lower alloys, lower costs (of products).
2. 2) The development of new organic film-based coatings that mimic the design of stainless steel, applied to low-carbon, cold-rolled and galvanized steel; which provide the same appearance and provide adequate corrosion resistance in the areas mentioned.

Problems to solve

In the first case, the price of steel continues to be high, since the substrate is made of stainless steel, and the corrosion resistance required for certain uses is not as high as that of stainless steel. However, their great advantage lies in their metallic appearance and the possibility of different designs.

In the second case, the appearance of steel is not as good as that of stainless steel itself, it does not have that of metal but that of plastic. However, the corrosion resistance is sufficient for a large number of uses and the price is much more competitive.

In conclusion, the work of the large steel plants in the market has been to try to improve the aesthetics of a low-carbon substrate by using mechanical methods to mimic that of stainless steel and by applying a series of organic layers to increase the resistance to corrosion.

• L'emboutissage du matériau, suivant un essai ECCA T6, est inférieure à 8mm (valeur requise dans le secteur électrodomestique, des ascenseurs, etc.) (L'adhérence du revêtement organique est inférieur à celle qui est requise)
• La résistance au pliage, suivant un essai ECCA T7, est de 0,5-1T (valeur requise 0-0,5T) (le revêtement métallique se fissure et entraîne la fissure du revêtement organique).
• La résistance à la corrosion en chambre à brouillard salin selon un essai ECCA T8 est inférieure à 1 50 heures (elle doit durer 300 à 500 heures) (le matériau se corrode et devient inutilisable - ECCA signifie European Coil Coating Association, ses codes d'essai sont normalisés pour ce secteur et pour d'autres secteurs, de plus ils sont en corrélation avec les normes ISO, EN et ASTM).

But the known products (metal panels) are not satisfactory since they do not even meet the requirements of the aforementioned industrial sectors because:

• The stamping of the material, according to an ECCA T6 test, is less than 8mm (value required in the electrical sector, elevators, etc.) (The adhesion of the organic coating is lower than that required)
• The resistance to bending, according to an ECCA T7 test, is 0.5-1T (required value 0-0.5T) (the metal coating cracks and causes cracking of the organic coating).
• The salt spray chamber corrosion resistance according to an ECCA T8 test is less than 1 50 hours (it must last 300 to 500 hours) (the material corrodes and becomes unusable - ECCA stands for European Coil Coating Association, its codes of test are standardized for this sector and for other sectors, in addition they correlate with ISO, EN and ASTM standards).

The Applicant has studied the problem and, based on the tests carried out in his installations, he explains the main cause of the problem in this way: if one acts mechanically on a metal substrate of low carbon steel coated with protective metal (for example: zinc, chromium, tin, ...) which improves its resistance to corrosion (zinc in galvanized steel, tin in tinplate or chrome in sheet metal chromed), the protective metal is destroyed and even if an organic coating is applied, the behavior of the material is not valid.

He is known by the patent US 2006/198988 A1 a metal panel of a ferrous metal substrate with an eroded metal coating that has the outward appearance of stainless steel.

He is known by the patent JP S63 140098 a metal panel of a steel substrate with the sides eroded and with Zn coating by electroplating.

The solution proposed by the Applicant consists in reversing the coating and satin phases over time, by proposing a new process where satin is first applied and then coated.

We will expose other problems and their solution further.

1. a) d'abord, un satinage mécanique par brunissage à l'oxyde d'aluminium dont la vitesse est de 4 à 20 mètres/minute ; et ensuite
2. b) un revêtement de la plaque satinée : elle est revêtue par électrolyse, d'une couche de métal protecteur choisi entre le chrome, l'étain et le zinc dont la quantité est comprise entre 40 mg/m² et 500 mg/m².

Specifically, the proposed process for the manufacture of a metal panel from a low carbon steel plate between 0.10% and 0.20% and a thickness of 0.10mm and 2.00mm is to subject the plate to two treatments:

1. a) first, a mechanical burnishing with aluminum oxide burnishing whose speed is 4 to 20 meters / minute; and then
2. b) a coating of the satinised plate: it is electrolytically coated with a protective metal layer selected from chromium, tin and zinc, the amount of which is between 40 mg / m ² and 500 mg / m ² .

This manufacturing process also includes baths for cleaning the steel plate covered by the protective metal sheet. The last bath is made with water with a conductivity less than 50μS / cm.

1. 1) Le substrat de base est un acier à faible teneur en carbone (de 0,10% à 0,20%) laminé à froid ou galvanisé ou en fer blanc d'épaisseur (de 0,10 mm à 2,00mm) ce qui réduit le coût du produit.
2. 2) Ce substrat est satiné mécaniquement par un processus semblable à celui de l'acier inoxydable, ce qui lui donne un design et une esthétique comparables à l'acier.
3. 3) Ensuite, le satiné est revêtu d'une fine couche de chrome, d'étain ou de zinc (de 40mg/m2 à 500mg/m²) qui remplit deux fonctions. D'une part, le métal protecteur agit pour améliorer la résistance à la corrosion du métal de base, et d'autre part, il rend la surface plus homogène et l' aspect plus brillant et métallique, semblable à celui de l'acier inoxydable. En déposant par électrolyse cette fine couche de chrome après le satinage mécanique, on évite que le satinage endommage le matériau protecteur qui reste intact et permet une bonne adhérence du revêtement organique.

If we apply the proposed process, we get this:

1. 1) The base substrate is low carbon steel (0.10% to 0.20%) cold rolled or galvanized or tinplate (0.10mm to 2.00mm) which reduces the cost of the product.
2. 2) This substrate is mechanically satinized by a process similar to that of stainless steel, which gives it a design and aesthetics comparable to steel.
3. 3) Next, the satin is coated with a thin layer of chromium, tin or zinc (from 40mg / m2 to 500mg / m ² ) which fulfills two functions. On the one hand, the protective metal acts to improve the corrosion resistance of the base metal, and on the other hand, it makes the surface more homogeneous and the appearance brighter and metallic, similar to that of stainless steel . By electrolytic deposition of this thin layer of chromium after mechanical saturation, we avoid satin damages the protective material which remains intact and allows good adhesion of the organic coating.

Thanks to this new process, we can obtain the values requested by the customers during the tests mentioned previously; and the application to said sectors of a stainless-like aesthetic product, with more acceptable mechanical and anticorrosive properties and at a much lower cost.

Description of the process

1. 1) Le substrat de base du produit est un acier à faible teneur en carbone (de 0,10% à 0,20%) (Ses caractéristiques mécaniques, limite d'élasticité, limite de rupture et d'allongement correspondent aux normes), son épaisseur est comprise entre 0,10mm et 2,00mm ,il est satiné mécaniquement au moyen de rouleaux ou de bandes de brunissage d'oxyde d'aluminium pour toutes les finitions standards homologuées internationalement (degrés 60-320 ou finition "Scotch Brite"- par un processus dont le classement de vitesse est de 4 à 20 mètres/minutes.)
2. 2) Le substrat satiné est revêtu, au moyen d'électrolyse, par un métal protecteur (chrome, étain ou zinc) (cela pourrait être un alliage entre eux) d'une quantité comprise entre 40 mg/m² et 500 mg/m². On obtient une surface homogène, brillante et qui garde le design satiné sur le substrat de base
   On appelle métal protecteur le métal qui sera corrodé, par les conditions du milieu ambiant, à la place du fer (Fe), composant de l'acier.
3. 3) Le matériau obtenu est traité chimiquement au moyen d'une série de bains pour le nettoyage, le dégraissage chimique et les lavages, dont le dernier est réalisé avec un bain d'eau déminéralisée d'une conductivité inférieure à a 50µS/cm.
4. 4) Le matériau est préparé pour recevoir un adhésif sur le côté extérieur ou la partie visible; la résine de base peut être en polyester, en polyuréthane ou acrylique, sous la forme d'une feuille de 10 à 50 micromètres, humide (avant le processus de séchage) et elle reçoit sur le coté intérieur ou non visible une impression en polyester, polybutyral, époxy ou polyuréthane. Le matériau est introduit dans un four où le métal peut atteindre une température de 150 à 210°C afin de sécher le revêtement organique liquide ; à sa sortie, on lui applique un film PET qui scelle le produit.
5. 5) (Phase optionnelle) Après les bains pour le nettoyage, et en option, on peut appliquer, pour augmenter encore plus la résistance à la corrosion des produits particulièrement agressifs, une impression transparente à l'eau, avec laquelle on déposera une fine couche d'un matériau noble (par exemple : zirconium, titane) (inférieure à 10mg/m²). Cette impression est séchée dans un four qui permet d'obtenir un métal à 100°C, afin de faire évaporer l'eau de l'impression.
6. 6) (2e phase optionnelle) De manière optionnelle, on peut placer un film protecteur après l'application du film PET pour permettre au client l'usinage de l'acier sans endommager les revêtements.

The process consists of the following phases:

1. 1) The base substrate of the product is a low carbon steel (from 0.10% to 0.20%) (Its mechanical characteristics, yield strength, ultimate yield and elongation limit correspond to the standards), its thickness is between 0.10mm and 2.00mm, it is mechanically satinized by means of rollers or aluminum oxide burnishing strips for all internationally approved standard finishes (60-320 degrees or "Scotch Brite" finish) - by a process whose speed classification is 4 to 20 meters / minutes.
2. 2) The satin substrate is coated, by means of electrolysis, with a protective metal (chromium, tin or zinc) (this could be an alloy between them) in an amount of between 40 mg / m ² and 500 mg / m ² . A homogeneous, glossy surface that keeps the satin design on the base substrate
   Protective metal is the metal that will be corroded by environmental conditions instead of iron (Fe), a component of steel.
3. 3) The obtained material is chemically treated by means of a series of baths for cleaning, chemical degreasing and washes, the last of which is carried out with a demineralized water bath with a conductivity lower than 50 μS / cm.
4. 4) The material is prepared to receive an adhesive on the outer side or the visible part; the base resin may be of polyester, polyurethane or acrylic, in the form of a sheet of 10 to 50 microns, wet (before the drying process) and it receives on the inner side or not visible a polyester printing, polybutyral, epoxy or polyurethane. The material is introduced into an oven where the metal can reach a temperature of 150 to 210 ° C to dry the liquid organic coating; when it comes out, we apply a PET film that seals the product.
5. 5) (Optional phase) After the baths for cleaning, and optionally, to increase even more the corrosion resistance of particularly aggressive products, a transparent impression with water, with which a thin layer will be deposited a noble material (for example: zirconium, titanium) (less than 10 mg / m ² ). This printing is dried in a furnace which makes it possible to obtain a metal at 100 ° C., in order to evaporate the water of the printing.
6. 6) (optional second phase) Optionally, a protective film can be placed after application of the PET film to allow the customer to machine the steel without damaging the coatings.

The product resulting from this process shows significant improvements over a conventional product, the following tests demonstrate these improvements. testing Conventional Product Product of the invention ECCA T6 (Erichsen stamping) Less than 6mm greater than 8mm ECCA T7 Folding Resistance 0.5-1T (cracking substrate) OT without cracking ECCA T8 Resistance to corrosion in Salt fog chamber Less than 150h 300-500h ECCA T9 Resistance to water immersion Less than 100h 500h ECCA T13 Resistance to aging by heat 200h at 120 ° C 500h at 120 ° C

Examples: Example 1

Substrate: Cold rolled steel with a low carbon content (0.12%) and a thickness of 0.50mm.

Satin: The satin process applied mechanically to the substrate by means of aluminum oxide burnishing to a standard degree and called "Scotch Brite" on the market, and which mimics the finish of stainless steel.

Chrome coating: chromium deposit by electrolysis on the satin substrate, a layer equivalent to 140mg / m ² .

Chemical treatment: chemical cleaning by means of a series of degreasing and washes, the last of which is carried out with demineralized water of conductivity lower than 50μS / cm.

Application of liquid organic coating: application of a polyester adhesive (15 microns) on the visible side and an epoxy impression (10 microns) on the hidden side. Drying of the product in an oven, metal temperature above 150 ° C.

Application of a PET film: brilliant PET film.

Application of a protective film: protective film (50 microns thick).

Example 2

Substrate: Low carbon cold rolled steel (0.12%) and 0.40mm thick.

Satin: a satin process applied mechanically to the substrate by aluminum oxide burnishing of a standard degree and referred to in the "grade 220" market; which looks like the finish of stainless steel.

Chromium coating: Zinc deposit by electrolysis on the satin substrate, with a layer equivalent to 50 mg / m ² .

Chemical treatment: chemical cleaning by means of a series of degreasing and washes, the last of which is carried out with demineralized water with a conductivity lower than 50μS / cm. Application of water printing to apply titanium in quantities of less than 10 mg / m ² .

Application of liquid organic coating: application of an acrylic adhesive (25 microns) on the visible side and an epoxy-polyester printing (10 microns) on the hidden side. Drying of the product in an oven at a metal temperature of 150 ° C.

Application of a PET film: tinted PET film.

Application of a protective film: film of 50 microns thick.

Example 3

Substrate: Low carbon galvanized steel (0.12%) and 0.60mm thick.

Satin: The satin process applied to the substrate mechanically using aluminum oxide of a standard degree and referred to as "Scotch Brite"; it looks like the finish of stainless steel.

Chrome coating: Zinc deposition by electrolysis on the substrate saturated with a layer equivalent to 100mg / m ² .

Chemical treatment: chemical cleaning by means of a series of degreasing and washes, the last of which is carried out with demineralized water with a conductivity lower than 50μS / cm. Application of an impression with water to apply Zirconium in an amount of less than 10 mg / m ² .

Application of liquid organic coating: application of a polyester adhesive (15 microns) on the visible side and an epoxy-polyester printing (10 microns) on the hidden side. Drying the product in the oven; metal at 150 ° C. at a metal temperature of 150 ° C.

Application of a PET film: transparent matte PET film.

Application of a protective film: protective film of 50 microns thick.

Claims (5)

1. Process of manufacture of a metal panel, characterized in that a sheet of cold-rolled Steel, galvanized or low carbon tinplate between 0.10%-0.20% and thickness between 0.10-2.00mm is submitted:

   a) In a primary phase, to a mechanical satin finish with sanding with aluminium oxide sandpaper: The sanding speed is between entre 4-20 metres/minute, and following this,

   b) to a second phase in which the satin finished sheet is covered by electroplating, with a layer of a sacrificial anode chosen between chrome, tin and zinc with a quantity of between 40-500mg/m².
2. A process of manufacture of a metal panel, according to the foregoing claim, characterized in that the steel sheet already covered with the layer of metal anode is subjected to cleaning baths, the last of these with water with conductivity of less than 50µS/cm.
3. A process of manufacture of a metal panel, according to the foregoing claims, characterized in that after the cleaning baths, a transparent primer that is water based with a noble material is applied, to deposit a fine layer with a quantity of less than 10mg/m² of zirconium or titanium, then proceeding to the evaporation of the water from the primer.
4. A process of manufacture of a metal panel, according to the foregoing claims, characterized in that afterwards an adhesive is a applied, on the outer face or exposed part, whose base resin can be polyester, polyurethane or acrylic, in a layer of 10-50 wet microns (before the curing process) and a polyester primer, polybutyral, epoxy or polyurethane on the inner face or unexposed part, introducing the metal panel in an oven at a metal temperature of 150-210°C to cure the liquid organic coating, and on leaving, a PET film is applied which seals the product.
5. A metal panel, characterized in that it is obtained by the manufacturing process of claim 1.