AU774014B2

AU774014B2 - Method for producing coated metal surfaces and the use of said metal surfaces

Info

Publication number: AU774014B2
Application number: AU20104/01A
Authority: AU
Inventors: Heribert Domes
Original assignee: Chemetall GmbH
Current assignee: Chemetall GmbH
Priority date: 1999-12-17
Filing date: 2000-12-14
Publication date: 2004-06-10
Anticipated expiration: 2020-12-14
Also published as: AU774014C; ES2203539T3; WO2001043888A2; DE19961411A1; ZA200205289B; EP1242193B1; CA2394235A1; DE50003490D1; ATE248032T1; EP1242193A2; WO2001043888A3; AU2010401A; US20030051772A1; CN1409657A

Abstract

The invention relates to a method for producing coated metal surfaces at a coating speed of at least 25 m per minute during the application of a pre-treating agent to a cleaned and/or pickled metal surface. The inventive method is characterized by applying at least one pre-treating agent to at least one surface of a metal body after cleaning and/or pickling the metal surface to be treated. At least one lacquer layer is applied to a part of the pre-treated surface, the coating produced only by the pre-treating agent and not by the lacquer being used as the treatment layer instead of a priming or pre-treatment layer. The invention further relates to a method for producing coated metal surfaces at a coating speed of at least 25 m per minute during the application of a pre-treating agent to a cleaned and/or pickled metal surface. The inventive method is characterized by applying at least one pre-treating agent to at least one surface of a metal body after cleaning and/or pickling the metal surface to be treated. At least one lacquer layer is applied to at least a part of the pre-treated surface, the coating produced only by the pre-treating agent being used as the treatment layer instead of a priming or pre-treatment layer.

Description

-1- Method for Producing Coated Metal Surfaces and their Use The present invention relates to a method for producing coated metal surfaces in which the coating can be carried out at high speed. Such coatings are often used under the description "coil coating" to coat strip materials.

The known high-speed coating methods have the disadvantage that the pretreatment and the priming (primer) are applied in two separate steps.

The object of the invention is to provide a process for the large-scale industrial production of lacquered strip materials in which the pretreatment and priming can be applied in only one work stage.

This object is achieved by a process for producing coated metal surfaces at a coating speed of at least 25 m per minute in the application of a pretreatment agent to a cleaned and/or pickled metal surface, which is characterised in that at least one pretreatment agent, in particular a solution and/or dispersion, is applied to at 2 least one surface of a metal body after a cleaning and/or 25 a pickling of the metal surface to be treated and at least o*ooo one lacquer layer is then applied to a part of the :pretreated surface, with the coating produced only using a pretreatment agent and not using a lacquer being used, instead of a pretreatment layer and a priming layer, as 30 treatment layer.

•o .According to the present invention, there is provided a method of producing a coating on a metal surface of a metallic strip having at least a first side and a second side, the coating being applied at a coating speed of at least 25 m per minute, the method comprising forming a coating by: H: \veronica\keep\speci\20104-02 (amend spec) .doc 19/04/04 2 applying at least one pretreatment agent to at least one side of the metallic strip to form a pretreated surface; applying to at least a portion of the pretreated surface at least one lacquer layer comprising at least one powder lacquer layer which is stoved; wherein the coating comprising at least one pretreatment agent and no lacquer layer is used as a treatment layer, instead of being used as a pretreatment layer or primer layer; and the coating comprising at least one pretreatment agent and at least one lacquer layer uses the at least one pretreatment agent as a pretreatment layer.

Preferably, the coating comprising at least one pretreatment agent and no lacquer layer, is on a different side of the metallic strip to the coating comprising at least one pretreatment agent and at least one lacquer layer.

Preferably, the pretreatment agent used to coat the second side of the metallic strip is different to the pretreatment agent used to coat the first side of the metallic strip.

Preferably, the side that is not intended to be "subsequently lacquered/primed is coated with a pretreatment agent containing an organic resin.

*e Preferably, the pretreated surface or surfaces form one side of a strip, in which optionally at least one of the narrow edge surfaces of the strip may also be partially pretreated.

ooe The coating speed is preferably 40 to 600 m per minute, 35 particularly preferably 75 to 160 m per minute. The treatment layer thereby assumes the functions of the primer. The other part of the pretreated surface is H:\veronica\keep\speci\20104-02 (amend spec).doc 19/04/04 2a subsequently no longer coated with a lacquer in the strip coating device.

The method according to the invention may be employed so that moisture or residual moisture is retained in the applied pretreatment layer until lacquering is performed, in order to adjust the necessary electrical conductivity of the pretreated surface for the application of the lacquer layer.

The metal surface may before the pretreatment contain in particular aluminium, iron, copper, magnesium, zinc and/or tin and may preferably consist of an aluminium alloy, a hot-dip galvanised or electrolytically galvanised iron material, a steel, a full zinc material in the form of strips or metal sheets, or tinplate. In this connection ee H:\veronica\keep\speci\20104-02 (amend spec).doc 19/04/04 Wo 01/43988 PCT/EPOO/12745 the bodies may be flat or shaped, or may be provided with recesses, such as for example with a perforated structure.

The recesses of a perforated plate may all have the same geometry and size, or may optionally also have different geometries and sizes, for example circular holes, elongate holes or slits.

The cleaning and/or the pickling of the metal surfaces may be carried out by spraying and/or brushing with a cleaning and/or pickling solution or immersion in a bath of this solution.- The pretreatment of the cleaned and/or pickled surface may be performed by spraying and squeezing out, for example with a roller, by spraying and blowing off, for example with compressed air, by immersion and squeezing out, for example with a roller, by immersion and blowing off, for example with compressed air or in a roll-coat process.

With the roll-coat process the treatment liquid is applied with a coating roller in or against the direction of movement of the strip. In all these process variants, no subsequent rinsing is performed in order to prevent removing and/or damaging the applied layer and to avoid rinse water loaded with chemicals, which for environmental reasons, would have to be post-treated in a complex procedure.

The pretreatment agent may be a preparation containing a polymer dispersion with at least one resin from the group consisting of acrylate, epoxide, phenol, polyester, silicone polyester, polyurethane, styrene and ureaformaldehyde based resin or a mixture thereof and/or a mixed polymer. The preparation contains, apart from volatile constituents, a non-volatile film-forming mixture, WO 01/43888 PCT/EPOO/12745 4 The preparation may contain at least one resin as solution and/or as dispersion. The preparation may contain, apart from resin(s), at least one inorganic additive in dissolved form and/or as a finely divided powder, for example a carbonate, chromate, oxide, phosphate, silicate or sulfate.

The pretreatment agent may also be a resin-free preparation, with it being possible for the preparation to contain aluminium, fluoride, hydrofluoric acid, phosphate, phosphoric acid, trivalent and/or hexavalent chromate, chromic acid, silicate, silane, tannin, titanium, zinc, zirconium and/or self-organising molecules, for example based on phosphonates, carboxylic acids, thiols and/or silanes.

For the application to a metal strip a different pretreatment agent may be chosen for one side of the strip than for the other side, with it being possible for the side not intended to be subsequently lacquered to be coated with a pretreatment agent containing organic resin. For example only one side of the strip, say the upper side, is possibly lacquered, whereas, on the opposite side, the pretreatment acts as a final treatment.

After the application of the treatment agent the layer may either be partially dried or completely dried. This may be carried out especially with uniform strip speeds and when using existing ovens by a shorter residence time under the active drying conditions, by a lower temperature in the oven, and/or by a reduced air movement for the drying of the strip.

Preferably at least one side of the pretreated surface is coated with an organic coating that hardens sufficiently PCT/EPOO/12745 WO 01/43888 5 and/or crosslinks in a time from 1 second up to 3 minutes, particularly preferably from 5 seconds up to 2 minutes.

For the coating of the pretreated surface, a powder lacquer, in particular a powder lacquer having good mechanical properties, high scratch resistance, good adhesion and high flexibility as regards forming and shaping, is preferably applied and stoved. The powder lacquer may in this connection be applied by spraying, fluidised-bed powder sintering and/or powder cloud technology and stoved. Powder cloud technology is described in, inter alia, EP-A-0 678 466. Instead of by conventional circulating air drying or fluidised air drying, the stoving may be carried out by, in particular by conductive drying using magnetic materials, and/or by infra-red drying, in particular in the near infra-red

(NIR).

The pretreatment layer and/or treatment layer may, after complete drying, have a layer thickness in the range from 0.1 to 50 pm, preferably in the range from 0.5 to 10 pm, particularly preferably in the range from 1 to 3 inm.

After the crosslinking, the stoved lacquer layer that is contained on the pre-treatment layer may have a layer thickness in the range from 5 to 1000 pm, preferably in the range from 10 to 400 pin, and particularly preferably in the range from 15 to 60 pim. When using PVC plastisols it is possible to recommend selection of a layer thickness in the range from 100 to 300 pm.

wo 01/43888 PCTI/EPOO/12745 6 In a preferred embodiment of the method according to the invention a one-layer cover lacquer is applied as a single lacquer to the strip to be coated.

A treatment layer that performs the function of a pretreatment and at the same time that of a primer can be formed with the pre-treatment agent. The primer in this connection performs the function of corrosion prevention, satisfies the adhesion and flexibility requirements, and to a minor extent also performs an aesthetic function.

There may be used for the powder lacquer a powder for a single-colour unstructured coating, a powder for a multicolour unstructured coating, and/or a powder for a multicolour structured coating.

The coated surface may be protected, in particular against mechanical damage, for example during storage, transportation and further processing, at least partially by a film or adhesive film.

The coated bodies may optionally be shaped, cut especially in the longitudinal and/or transverse direction and optionally re-formed, for example beaded, rollformed, deep-drawn and/or edged.

The products formed by the method according to the invention may be used as internal and external panelling, equipment panelling, e.g. for domestic appliances and small electrical instruments, in particular with decorated external panelling, perforated metal sheets, especially for loudspeakers and sound insulating cladding, space dividers, partitions, furniture units, shelving, internal panelling for vehicles and aircraft, such as for example 7 dashboards/instrument panels, frame and frame constructions, facing materials and lighting installations.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

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Claims

2. A method of producing a coating on a metal surface according to claim 1, in which the coating comprising at least one pretreatment agent and no lacquer layer is on a different side of the metallic strip to the *0000 25 coating comprising at least one pretreatment agent and at least one lacquer layer. oooe "i A method of producing a coating on a metal surface according to claim 2, in which the pretreatment 30 agent used to coat the second side of the metallic strip 00.. is different to the pretreatment agent used to coat the C* first side of the metallic strip. CCo.
4. A method of producing a coating on a metal surface according to claim 2 or 3, in which the side that S"is not intended to be subsequently lacquered/primed is coated with a pretreatment agent containing an organic H:\veronica\keep\speci\20104-02 (amend spec) .doc 19/04/04 9 resin. A method of producing a coating on a metal surface according to any one of the preceding claims, in which any moisture or residual moisture in the applied pretreatment layer is retained until lacquering in order to adjust the necessary electrical conductivity of the pretreated surface for the application of the lacquer layer.
6. A method of producing a coating on a metal surface according to any one of the preceding claims, in which the metal surface contains aluminium, iron, copper, magnesium, zinc and/or tin before application of the pretreatment agent.
7. A method of producing a coating on a metal surface according to claim 6, in which the metal surface contains an aluminium alloy, a hot-dip galvanised or electrolytically galvanised iron material, a steel, or a full zinc material.
8. A method of producing a coating on a metal surface according to any one of the preceding claims, in r oo which the pretreatment agent is applied by spraying and 25 squeezing out with a roller or by immersion and squeezing e ee o out with a roller or by a roll-coat process. S
9. A method of producing a coating on a metal surface according to any one of the preceding claims, in which the pretreatment agent is a preparation that contains a polymer dispersion with at least one resin selected from acrylate, epoxide, phenol, polyester, silicone polyester, polyurethane, styrene, urea- formaldehyde based resin or a mixture thereof and/or a S 35 mixed polymer. A method of producing a coating on a metal H:\veronica\keep\speci\20104-02 (amend spec).doc 19/04/04 10 surface according to any one of the preceding claims, in which the pretreatment agent is a preparation that contains at least one resin in the form of a solution and/or dispersion.
11. A method of producing a coating on a metal surface according to any one of the preceding claims, in which the pretreatment agent is a preparation which contains beside of resin(s)- at least one inorganic additive in a dissolved form and/or as a finely divided powder including a carbonate, chromate, oxide, phosphate, silicate or sulfate.
12. A method of producing a coating on a metal surface according to any one of the preceding claims, in which the pretreatment agent is a resin-free preparation that contains aluminium, fluoride, hydrofluoric acid, phosphate, phosphoric acid, trivalent and/or hexavalent chromate, chromic acid, silicate, self-organising molecules, silane, tannin, titanium, zinc, zirconium or a mixture thereof.
13. A method of producing a coating on a metal surface according to any one of the preceding claims, in 25 which the metal surface applied with the pretreatment agent is either partially dried or completely dried.
14. A method of producing a coating on a metal surface according to any one of the preceding claims, in 30 which at least one side of the metal surface applied with the pretreatment agent is coated with an organic coating that hardens and/or crosslinks sufficiently in a time of 1 ":second up to 3 minutes. eeee 35 15. A method of producing a coating on a metal eeeee S• surface according to any one claims 1 to 13, in which at least one side of the metal surface applied with the H:\veronica\keep\speci\20104-02 (amend spec).doc 19/04/04 11 pretreatment agent is coated with an organic coating that hardens and/or crosslinks sufficiently in a time of seconds up to 2 minutes.
16. A method of producing a coating on a metal surface according to any one of the preceding claims, in which for the coating of the pretreated surface, a powder lacquer having good mechanical properties, high scratch resistance, good adhesion and high flexibility with regard to forming and shaping is applied and stoved.
17. A method of producing a coating on a metal surface according to any one of the preceding claims, in which the powder lacquer is applied by spraying, fluidised-bed powder sintering and/or powder cloud technology and then stoved.
18. A method of producing a coating on a metal surface according to any one of the preceding claims, in which the pretreatment layer and/or treatment layer has a layer thickness in the range from 0.1 to 50 Cpn after completely drying.
19. A method of producing a coating on a metal :oo: 25 surface according to claim 18, in which the pretreatment i. layer and/or treatment layer has a layer thickness in the range from 0.5 to 10 pm after completely drying. A method of producing a coating on a metal surface according to claim 18, in which the pretreatment layer and/or treatment layer has a layer thickness in the range from 1 to 3 pm after completely drying.
21. A method of producing a coating on a metal o 35 surface according to any one of the preceding claims, in which the stoved lacquer layer after crosslinking has a layer thickness in the range from 5 to 1000 gm. H:\veronica\keep\speci\20104-02 (amend spec) .doc 19/04/04 12
22. A method of producing a coating on a metal surface according to any one of claims 1 to 20, in which the stoved lacquer layer after crosslinking has a layer thickness in the range from 10 to 400 pm.
23. A method of producing a coating on a metal surface according to any one of claims 1 to 20, in which the stoved lacquer layer after crosslinking has a layer thickness in the range from 15 to 60 gm.
24. A method of producing a coating on a metal surface according to any one of the preceding claims, in which a single-layer cover lacquer is applied as sole lacquer at high speed. A method according to any one of the preceding claims, in which a treatment layer that performs the function of a pretreatment and primer is formed with the pre-treatment agent.
26. A method of producing a coating on a metal surface according to any one of the preceding claims, in which a powder for a single-colour unstructured coating, a 25 powder for a multicolour unstructured coating, and/or a powder for a multicolour structured coating is used. o .27. A method of producing a coating on a metal surface according to any one of the preceding claims, in which the coated surface of the metallic strip is protected at least partially by a film or adhesive film. a or
28. A method of producing a coating on a metal surface according to any one of the preceding claims, in 35 which the coated surfaces are shaped, formed or cut in the longitudinal and/or transverse direction. H: \veronica\keep\speci\20104-02 (amend spec) .doc 19/04/04 13
29. A method for producing coated metal surfaces according to claim 28, in which the coated surfaces are additionally reformed using a process such as beading, roll-forming, deep-drawing and/or edging. A method for producing coated metal surfaces according to any one of the preceding claims in which the metal surface undergoes cleaning and/or pickling before the pretreatment solution is applied.
31. A method of producing a coating on a metal .surface according to claim 30, in which the cleaning and/or the pickling is carried out by spraying and/or brushing with a cleaning and/or pickling solution or immersion in a bath of a cleaning and/or pickling solution.
32. Use of a product produced by the method according to claims 1 to 31 as internal and external panelling, equipment panelling, for domestic appliances and small electrical instruments, decorated external panelling, perforated metal sheets, loudspeakers, sound insulating cladding, space dividers, partitions, furniture units, shelving, internal panelling for vehicles and aircraft, 25 dashboards/instrument panels, frame and frame constructions, facing materials or lighting installations. 30 Dated this 19th day of April 2004 CHEMETALL GmbH By their Patent Attorneys GRIFFITH HACK Fellows Institute of Patent and 35 Trade Mark Attorneys of Australia *e H: \veronica\keep\speci\20104-02 (amend spec) .doc 19/04/04