DE2330131A1 - METAL SURFACE COATING METHOD - Google Patents

Description

PATENT LAWYERS

DR. ING. VAN DERWERTH DR. FRANZ LEDERER

21 HAMBURG 9O ε MUNICH 8C

WILSTORFER STR. S3 · TEL. CD4 IH 77 08 oil LUCtLE-GRAHN-STR. S3 · TEL. ΙΟβ 11> 47 39 47

Munich, June 13, 1973

963

L / Lo / th

AMCHiM PRODUCTS, INC. Brookside Avenue, Ambler, Pennsylvania, U.S.A.

Process for coating metal surfaces

The invention relates to an improved method for coating metal surfaces. Under the term "metal surfaces", As used in the description, not only bare metal surfaces, but also such metal surfaces are closed understand which have been provided with a layer of an inorganic primer, e.g. B. a so-called chemical conversion coating such as a phosphate or chromate coating or a so-called anodically applied coating. In particular, the invention relates to a method for coating metal surfaces with resin composite coatings, which are built up on a base coat using the chemical deposition process that has recently been developed of organic / inorganic coating was applied.

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OKUTSCMC "AH Κ AO .. HARtURO 93/30" I " f O STSCH (CKi HAMSURC 1179 90

TILIORAMMIi L (OERIRrATIMT MONCHIN

Different working methods for a chemical deposition of organic / inorganic coatings have been developed which - although they differ in certain details - all in all the immersion of an acid-etchable metal surface to be coated into an acidic, comprise aqueous resin dispersion, which attacks the metal surface and in this way metal ions in the dispersion generated, the structure of the metal ions thus generated in the vicinity of the metal surface to such a high level Local concentration leads to the otherwise stable dispersion causing a deposition of the resin on the metal surface becomes locally destabilized, causing the resin to deposit on the metal surface to form a coating is brought on, the strength and / or weight of which is a function of the immersion time, so that they are predicted and can be controlled. Such organic / inorganic coatings by chemical deposition must be clear from the conventional, A distinction can be made between quick-drying coatings, from which they differ in certain, basic properties, which are later on to be explained, differ. Conventional quick drying coatings include all types of resin coatings or coatings, regardless of whether they are clear and transparent or pigmented, whether they are self-curing are or a. Require drying or baking and independently from the application technique, including electrophoretic application techniques are included.

Procedures for chemical deposition of organic / inorganic coating have certain very distinct advantages compared to different, conventional ways of applying quick-drying coatings. So is one practically uniform deposition of the organic / inorganic coating over the entire metal surface in an easily controllable manner

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Even on the inaccessible parts of complex-shaped components or objects such as car bodies or household appliances, etc. ensured, and vice versa a surprisingly good and uniform deposition of the organic / inorganic coating even on the most exposed edges of cut metal sheets, etc. In In this regard, the procedures for preparing organic / inorganic coatings are generally conventional Spray paint or other now conventional working methods for applying quick-drying coatings even the electrophoretic and electrostatic coating procedures superior, since with the latter a uniform coating can only be achieved with a uniform electrical pressure can be achieved, which is practically impossible to achieve with complex-shaped components and objects.

On the other hand, procedures for chemical deposition of organic / inorganic coatings have some practical limitations, at least at the current stage of development. The metal surface to be coated must be immersed in the acidic, aqueous one Resin dispersion, and requires the complete immersion of a large metal component or article the use of immersion tanks, which contain very large volumes of the »acidic, aqueous resin dispersion, among Many thousands of liters of it. This in turn makes it more difficult for the manufacturer to find the properties of the organic / inorganic coating to be applied change, be it in terms of color, gloss, transparency or opacity, abrasion resistance, the chemical stability, corrosion resistance, weather resistance and / or adhesion. Small adjustments to one these purposes, e.g. B. to achieve a color match, can only be done with difficulty, since any

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Additives in the total amount of the large volume of the Dispersion must be homogenized while larger Changes even emptying, cleaning, and refilling the immersion tank, or using a different one Require immersion tank. These issues are likely to be most pressing for automobile manufacturers, on the one hand because of the size of the to be provided with color Sheet metal body and on the other hand because of the frequent changes of color and shade that are obviously required although automotive body parts are likely because of the harsh conditions they are exposed to in use More than most metal objects, excellent all-round protection for even the least require accessible parts by working methods for chemical deposition of organic / inorganic coatings can be done.

The object of the invention is to provide an improved method for resin coating metal surfaces, which optimal results combined with an all-round, through the working method of the chemical deposition of an organic / inorganic coating of possible protection together with the diversity of the more conventional working methods for quick-drying ones Coatings with a view to minor adjustments or major changes in the overall properties of the Ensures the coating.

The method of the present invention for forming a composite resin coating on acid-etchable metal surfaces is characterized in that the acid-etchable, to be coated Metal surface is first immersed in an acidic, aqueous resin dispersion in which a resin is used for a base coat dispersed in an aqueous phase containing an acid which corrodes the metal surface to produce metal ions

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is, the metal ions the otherwise stable dispersion in the vicinity of the metal surface with the deposition of a practically uniform organic / inorganic coating containing the base resin then destabilize that the metal surface in the acidic, aqueous Harsdispersion at such a temperature and for such a period of time that the organic / inorganic coating will then hold the the desired weight and / or the desired thickness, that the surface thus coated is then removed therefrom and if appropriate, the resulting organic / inorganic coating is aftertreated for solidification, after which at least another quick-drying coating is applied thereon and that the quick-drying coating is used to form a Unit of the resulting composite coating on the underlying Metal surface hardens.

The initial stage of the application of a chemically deposited, organic / inorganic coating ensures that at least the resulting base coat was an excellent one Adhesion and excellent anti-corrosive properties and is practically uniform in the desired thickness over the entire metal surface to be coated This way, hidden edges as well as exposed edges of cut edges are difficult to access Sheet metal, etc. are covered. The resulting base coat or primer coat is - as already described - not completely organic in nature, but partly also inorganic in nature, with a proportion of the etched away Contains metal ions in the form of their acid salts distributed within the resin coating itself and approximately in the form of a chemical conversion coating, which on the one hand with the underlying metal surface and on the other hand forms a unit with the overlying resin layer and on both

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adheres tightly. As far as this could be determined, forms the predominantly inorganic portion of the organic / inorganic base coat is a layer of measurable thickness and not merely a superficial or mono-molecular, inorganic one Layer, which is between the underlying metal surface itself and the overlying, mainly organic Layer is sandwiched. In addition, it contains metal (which at least partially consists of the metal ions originates, which has been dissolved away from the metal surface to be coated) in both the inorganic and the organic Layer forming the chemically deposited organic / inorganic basecoat, e.g. B. is the amount of iron in a basecoat formed on an iron or steel surface, often from about 0.1 to about 0.5% by weight (or even higher values) based on the total weight of the base coat. This is probably why that the chemically deposited, organic / inorganic basecoat has a combination of properties or particulars Has characteristics that are found in conventional, quick-drying, conventional application methods produced coatings or coatings v / earth not found.

These features make the chemically deposited, organic / Inorganic primer coating surprisingly very effective - after any solidification and / or Post-treatment, which is then necessarily or advantageously applied - as fixed or efficient Primer for one or more, other additional, quick-drying coatings that are applied using different, more versatile, conventional coating methods will. It should be noted that the chemically deposited organic / inorganic basecoat is likely as a result of the integration of the mainly inorganic layer

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Both the underlying metal surface and the overlying, mainly organic coating adheres naturally and from the start to the metal surface, so that, in contrast to quick-drying coatings, it can also be rinsed very vigorously immediately after deposition without removal it has little or no tendency to run off or drip off. Another essential feature of the chemically deposited organic / inorganic coating which makes it particularly suitable for use as a basecoat is that it can be applied in a controlled and uniform thickness. This is in contrast to procedures for conventional, quick-drying coatings by dipping a metal surface in a conventional latex of a quick-drying coating, since this forms a coating, the strength of which is mainly determined by the amount of resin solids in the latex, and where the strength achieved is the The resulting quick-drying coating when using a latex with any particular resin solids content cannot be controlled to any appreciable extent by varying the immersion time. In contrast, the acidic, aqueous resin dispersions which are used to deposit a base coating according to the invention form chemically deposited organic / inorganic coatings, the weights and / or thicknesses of which do not depend primarily on the particular resin solids content of the dispersion, but rather vary over a relatively wide range as a function of the immersion time of the metal surface in such a dispersion.

The invention does not primarily concern the details of the procedures involved in applying the chemically deposited, organic / inorganic primer applied as each of the possible work irons is more advantageous

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V / can be applied. The following, explained in more detail However, modes of operation can all be used to advantage.

In British patent specification 1 130 687 or the corresponding German patent application P 16 44 699 * 4, a method for applying certain resin coatings defined there to iron-containing or zinc-containing surfaces is described, this method bringing the surface into contact with a stable, aqueous dispersion of the resin, which has a pH of 1.6 to 3.8 and 0.4 to 5> 0 g of a simple fluoride, calculated as ΐ '~ per liter, 0.3 to 3 ₅ O g of hydrogen peroxide per liter and Has from 5 to 500 grams of this dispersed resin per liter, and wherein the resin remains stable in the dispersion for at least 24 hours at ambient temperature. Upon contacting, a resin coating is formed on the surface, after which the coated surface is dried.

In the German patent application P 22 29 017-1 a method for applying a coating of a film-forming material to the surface of a metal is described, which can be etched with an acid, and wherein the surface is brought into contact with a coating composition that film-forming material dispersed, dissolved or emulsified in an aqueous phase containing a metal corrosive acid, an oxidizing agent and a dispersing agent, the contacting being carried out for a period of time sufficient to cause the acid to attack the metal surface to generate metal ions allow, which are oxidized by the oxidizing agent on their entry into the aqueous phase with the formation of destabilizing ions, which can make the coating composition unstable and in this way lead to coagulation

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the composition of beliefs. Here the Overall stability of the coating composition as a result maintain that

a) a dispersant is added to the coating composition continuously or intermittently, so that there is essentially an adjustment to the build-up of the metal ion concentration; and or

b) Metal ions are removed, so that the build-up of the concentration metal ions are prevented,

and where the effective concentration of destabilizing metal ions is not more than J g / l when using the working technique a) alone or in conjunction with the working technique b) and to not more than 1.5 g / l "when using the Work technique b) is maintained.

In the German patent application P 22 11 490.5 is a method for applying a coating of an organic, resin-like material to a ferrous metal surface described in which the surface for a period of time required to form a coating of the desired thickness is brought into contact with an aqueous coating-forming composition which is a dispersion of a water-dispersible resin in an acidic, aqueous phase with a pH within the range of 1.6 to 5 * 0 and which from the beginning at least one contains a significant amount of iron (III) ions. In this process, the surface coated in this way is then applied rinsed and dried.

In the German patent application P 22 29 018.2 is a method for applying a coating of film-forming material to the surface of an acid etch accessible Metal described in which the metal surface n.'it a 'a coating-forming composition that a

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film-forming material in an aqueous, one the metal Has corrosive acid and an oxidizing agent-containing phase, is brought into contact and the so on the metal surface deposited coating then with an ITach rinsing solution which contains hexavalent chromium.

In the German patent application P 22 61 256.2 is a method for applying a coating of a film forming Material described on the surface of an acid etch accessible metal, the surface with a Coating composition '. Is brought into contact, which the film-forming material in an aqueous, a metal corrosive Acid-containing aqueous phase contains dissolved, dispersed or emulsified, the contacting being sufficient Period of time is carried out to form the acid attack on the metal surface. Metal ions carry out which into the aqueous phase causing the deposition of a coating of the film-forming material from the coating composition enter the metal surface, and thereby maintain the stability of the coating composition is that it is brought into contact with an ion exchange material which prevents the concentration of the metal ions in the composition as a whole except for a V / ert, which builds up the composition as a whole causing flocculation, coagulation, a gel formation or the like destabilized.

Of course, other procedures for forming the chemically deposited organic / inorganic basecoat can also be used can be used in addition to the working methods described above. The details of these procedures described above result from the patent applications mentioned, so that reference is made to these patent applications for further details can be.

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The conventional, quick-drying coating can take off any natural or synthetic film-forming, Resin-like material are formed, which is usually either on the bare wetal surfaces or applied to metal surfaces which have an inorganic coating on them, the corrosion-resistant or has adhesive properties, such as. B. an anodized coating or a chemical conversion coating. However, the material for the conventional, quick-drying coating should be selected in this way v / ground that the desired functional and / or decorative properties of the final composite coating be granted. The conventional, quick-drying coating is generally made of film-forming, resinous Materials produced in fluid ibrm d. H. either in liquid state - referred to as colors in the description for the sake of simplicity - or in the particulate, solid state - referred to as a powder in the description for the sake of simplicity - are applied using conventional methods Working methods applied to the chemically deposited, organic / inorganic base coat underneath will.

The film-forming component (s) the conventional, quick-drying coating can contain one or more of the naturally occurring oils or resins, either in a modified or unmodified state or one or more synthetic resins or a mixture be of natural and synthetic substances. This is how the material can be used for conventional, quick-drying coatings either an oil-based paint or a water-based paint, the latter often also referred to as latex. The term color used here includes both pigmented

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as well as non-pigmented, quick drying coating compositions like the paints or glazes or varnishes.

Examples of film-forming resinous materials used in Such colors can be used are linseed oil, wood oil (tung oil), oil-modified alkyd resins, epoxy resins, vinyl acetal, polyester, Polyamide, phenol, polyvinyl chloride, polyvinyl acetate, styrene-butadiene copolymer, polyacrylic resins or cellulosic resins.

The paint can be applied to the underlying chemically deposited organic / inorganic base coat in any suitable Ways to be applied, e.g. B. by brushing, dipping, flow coating, roller coating, application by means of Pressure curtain, by spraying including electrostatic spraying or even in appropriate cases by working methods for electrophoretic coating, e.g. B. in the manner described in German patent application P 22 27 289 · 5.

The conventional, quick-drying coating can do the same can be made from a coating or film-forming resinous powder. Examples of coating-forming resinous Powders that can be used are polyvinyl chloride, epoxy resin, polyamide, cellulose resin, polyester resin, polyethylene resin and polypropylene resin, polyacrylic resin, fluorocarbon powder including polytetrafluoroethylene and polyfluoroethylene propylene resin powders and chlorinated polyether powder.

Such coating resin powders can be produced by any of the conventional procedures such as flow coating, Flocculation can be applied by means of the fluidized bed process or the electrostatic spray process.

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It should be noted that some of the above-mentioned conventional ways of applying the conventional, quick drying coating require the use of electricity to create a potential difference between the metal surface to be coated and the quick-drying one Producing coating material, surprisingly, includes the previously applied, chemically deposited, organic / inorganic Primer coating, which is itself ascribed to have relatively high electrical insulating properties, which in fact somewhat has the electrical properties of the.metallic May affect the object, however, do not use such an electrical application technique for the quick-drying cover. In fact, it has been found that the electrical potential of the underlying metal surface can be easily increased to a value high enough to allow for such electrical deposition techniques to generate the required potential difference. Although this is usually not required, the application by electrical deposition techniques are further facilitated by using electrically highly conductive materials such as Metal or carbon powder or other particles be entered into the acidic, aqueous resin dispersion, so that the chemically deposited, organic / inorganic base coat , 'which is hereby given conductive properties or at least their electrical insulating properties be reduced.

The type of material selected for the conventional, quick-drying coating that for the top coating will of course depend on the nature of the properties desired in the coated article. The final, The top coating can be selected so that it provides a high gloss (enamel) or a low gloss (matt),

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furthermore, it is usually used in terms of its color retention, their resistance to external influences, their abrasion resistance and / or their chemical resistance .

In addition, it can be advantageous to place one or more intermediate sub-coatings between the chemically deposited, organic / inorganic base coat and the final, to place the top coating, and the resin materials for use in such intermediate sub-coatings should of course take a look at their chemical resistance in general and on their corro; 'iis strength in particular as well as with regard to the adhesion to the underlying, chemically deposited, organic / inorganic base coat as well as the final, top coat and selected with regard to their opacity will.

The thickness of the chemically deposited, organic / inorganic base coating or the quick-drying coating (Including both the final, topmost coating and, if applicable, all in between Sub-coatings) should with reference to the performance requirements be selected which are required for the particular application for which the composite coating provided, metallic objects are used. Though both major and minor. Thickness depending on the As a general guide, the thickness of the chemically deposited, organic / inorganic Base coat advantageously in the range of about 0.0025 mm to about 0.040 mm. The strength of any Intermediate sub-layer can also range from about 0.0025 mm to about 0.040 mm, and the thickness of the final, uppermost coating is advantageously in the range of about 0.018 mm to about 0.0-6 mm.

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BATH O.

The invention is illustrated in more detail by means of the following examples.

Examples 1 to 3

In these examples the production of a chemically deposited, organic / inorganic primer with subsequent spray application of a conventional, quick-drying Coating described.

A batch of sheet steel plates of 100 χ 305 nm were means with a commercially available, alkaline cleaning agent and then rinsed with cold water.

For chemical deposition of the organic / inorganic base coat each panel was immersed for 30 seconds at room temperature in an acidic, aqueous resin dispersion containing the contained the following ingredients in the specified proportions:

Component quantity

Base coat resin

(Trade name Catalin

A-1316) 100.0 g

Hydrofluoric acid 2.1 g

Hydrogen peroxide 1.7 g

Water, ^ to make up to 1 1

The flats were pulled out of the acidic, aqueous resin dispersion after 30 seconds and then rinsed with cold water. The coated and rinsed with water plates were then rinsed with a Schlußspüllösung during a time of 3 minutes at a temperature of about 54 ⁰ C, contained the following components and, more generally in the German patent application P corresponds described solution 22 29 018.2:

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hexavalent chromium 4.7 g / l

reduced chromium 4.7 g / l

Solution of water soluble
Polyacrylic acids (trade name Acrysol-A) 6.0 g / l

Phosphoric acid 3 »2 g / l

After this final rinsing, each of the coated and rinsed plates was ^{baked in an oven at 200 °} C. for 5 minutes. After stoving, panels provided with a primer coating, which were considered typical of this approach, were examined on this basis, with a coating g
became.

A weight of about 430 to about 450 mg / 0.093 m was found

The conventional, quick-drying coating was applied as follows: The one provided with the base coating Plates were divided into three groups A, B and C. Each group of plates was then treated with a different, quick drying Coating as the top coating coated as follows:

Group A - The panels were sprayed with an epoxy undercoat, followed by a top coat of melamine-modified alkyd resin. The total thickness of the composite resin coating formed was 0.0762 mm (3 mils).

Group B - The panels were spray coated with a thermosetting acrylic resin (trade name Duracron 100, commercial product of PPG Industries Inc.). The total thickness of the composite resin coating was 0.0305 mm (1.2 mils).

Group C - The panels were spray painted with a white alkyd resin based refrigerator / appliance paint. The total thickness of the composite resin coating was 0.0356 mm (1.4 mils)

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The resin coating used as the top layer was applied to the panels of the respective groups A, B and C with an air pressure paint spray gun, and the resulting,
quick drying coating was suitably cured.

The plates obtained, provided with a composite coating, x each group was then divided into series, which were subjected to the various test studies, the results of which are compiled in the following table I:

Table I : Test results on panels of groups A, B and C

test

Salt spray test standard ASTM B-117-61 5 % at 35 ° C (95 ° F) for 250 h

Impact test
3/4 "ball
65 inch-lbs.

Examination with a conical spike

Example panels
Kr.

Scribing error in mm (inch)

1 group A 5,556 (7/32 ")

2 Group B 2,381 (3/32 ")

3 Group C 1.537 (2/32 ")

Diameter error

none

7.937 mm radial tear

none

Inches of error

none

101.6 mm (4 ") radial tear

none

Examples 4 to 6

The following is the method of making a chemically deposited, organic / inorganic basecoat
described with the following application of a conventional, quick-drying coating.

A batch of steel plates similar to those used in Examples 1 through previous were processed in an identical manner cleaned and rinsed.

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The cleaned panels were then immersed in the same aqueous resin dispersion at the same temperature but for a longer period of time, namely for 3 minutes instead of 30 seconds. In this way, a heavier and thicker organic / inorganic basecoat was chemically deposited on each panel. After rinsing and baking in the same manner as in Examples 1 to 3, platters believed to be typical of this approach were examined, with their base weights determined to be ^{about 1370 to 1450 mg / 0.093 m.}

The plate provided with a base coating. ·; '"earthen gut as before divided into groups D, E and F and the respective Groups of the panels provided with the primer coating were then provided with different quick-drying coatings as the top coat in the following way:

Group D - The panels were modified with an epoxy undercoat and then with a topcoat of a melamine. Sprayed with alkyd resin. The total thickness of the bonded surface was 0.089 mm (3-5 mils).

Group E - The panels were spray-painted with a thermosetting aci * yl resin (tradename Duracron 100, product of PPG Industries Inc.). The total thickness of the composite resin coating was 0.051 mm (2.0 mils).

Group F - The panels were spray painted with a white alkyd resin based refrigerator / appliance paint. The total thickness of the composite resin coating was 0.051 mm (2.0 mils).

The panels provided with a composite coating an x * each group were then divided into rows which were subjected to the various test studies, the ¥ · · χ - results of sine in the following Table II zusammengesTeltt ¹

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Table II:

Investigations and results on plates of groups D, E and F

'read salt spray test impact test investigation ASTM B-117-61 standard 3/4 ". Ball with conical 5% at 35 ° C (95 F) 65 in-lbs. Dorm for 250 h

For boards, scratching error clearance in mm (inch) No.

4 Group D 7.937 (5/16 ")

5 Group E 6.350 (4/16 ")

6 Group F 3.175 (2/16 ")

Diameter- Inches error error

none 3/8 "(9.525) 11.12 mm 7/16" (101.6 mm) radi- radial Einales Tearing sen

none

none

Example 7

The following is the method of making a chemically deposited, organic / inorganic basecoat with the following electrostatic powder application.

Plates similar to the steel plates used in Examples 1 to 6 were first mixed with a commercially available solution of a alkaline cleaner and then rinsed with tap water.

The plates cleaned in this way were then stirred for a period of 5 minutes at room temperature in a continuously stirred, acidic, aqueous base resin dispersion immersed, the components of which were present in the following proportions:

Ingredients quantities

Base coat resin

(Trade name Pliolite 491) 100.0 g

Hydrogen peroxide 2.3 g

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Components

lien: gene S. 2 ,1 S. 5 , 9 S. 5 , 0 1 1

hydrofluoric acid phosphoric acid

Kiss pigment (aqueous dispersion of furnace black, product of Cities Service Co.)

Water, 'to top up

After immersion, the steel plates obtained, provided with a base coating, were removed from the resin dispersion, rinsed with tap water and then baked ^{at about 216 ° C. for 10 minutes.} The base coat thickness after bake was about 0.025 mm (1.0 mil).

The basecoated panels were then electrostatically sprayed with a white acrylic resin powder and again to converge the coating of the resin baked on top layer. The thickness of the resulting composite coating was 0.0787 to 0.0889 mm (3.1 to 3.5 nils).

The panels coated with the composite were then divided into series corresponding to the various different test investigations as listed below:

(a) Cleveland test with condensing moisture no failure after 240 h at 60 ^° C

(b) Salt spray test according to ASTM B-117-61

After 240 h in a 5% mist of neutral salt at 35 ° C the average scribe error was 1.587 mra (1/16 ").

(c) Conical mandrel test
no mistake

(d) Slack test (falling ball of 1/2 inch, i.e. 12.7% 100 inch-pounds)

no loss of color, slight radial tearing.

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Example 8

The following is the method of making a chemically deposited, organic / inorganic basecoat followed by a conventional, quick-drying coating.

Steel plates similar to those in Examples 1 to 7 were first cleaned and rinsed and then in an acidic, aqueous solution Resin dispersion immersed, which instead of a non-oxidizing acid together with an oxidizing agent, which is used for Oxidation of iron (II) ions to iron (III) ions capable is, contained only one oxidizing acid, namely nitric acid.

This acidic, aqueous resin dispersion based on nitric acid was set as follows:

Acrylic resin latex (goods

name Catalin A-1464-) 50 g Water, to make up to "Ί 1 nitric acid, to adjust

a pH of 2.5

The steel plates were immersed in this acidic aqueous resin dispersion for different periods of time, and all the plates received a chemically deposited, organic / inorganic base coat, the thickness of which was greater, the longer the Immersion period lasted.

The panels provided with a base coat in this way were then applied in the conventional manner subjected to a quick-drying coating, some panels by spraying paint, others by roller application, electrostatic powder coating and fluidized bed powder coating. In each case it was found that the resulting

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Composite coatings exhibited excellent corrosion resistance and complete durability in use.

From these results, it can be seen that the composite coated steel plates are excellent Have properties. The biggest advantage is the balance of excellent appearance and usability which are generally better than that of usually achievable coatings, either with chemically deposited, organic / inorganic coatings all biologically: or with the conventional, quick-drying coater. ^ :: alone. It is believed that the high degree of integration between the base coat and the metal surface on the one hand and the coating on top of it on the other hand together to these surprising results leads.

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Claims (12)

Claims A process for the formation of a resin composite coating on metal surfaces which can be etched by acid, characterized in that the metal surface to be coated and which can be etched by acid is first immersed in an acidic, aqueous resin dispersion in which a resin for a base coating is in one of the metal surfaces containing to produce metal ions corrosive acid, the aqueous phase is dispersed, wherein the metal ions are otherwise stable dispersion of a virtually uniform in the vicinity of the metal surface by deposition, the base resin containing, organic / inorganic coating thereon destabilize _t that the metal surface in acid, aqueous resin dispersion at such a temperature and for such a period of time that the organic / inorganic coating has the desired weight and / or the desired thickness on it, that the surface coated in this way is removed therefrom and, if necessary, the resulting, organic / inorganic coating is aftertreated for solidification, that at least one further, quick-drying coating is then applied to it and that the quick-drying coating is cured to form a unit of the resulting composite coating on the underlying metal surface. 2. The method according to claim 1, characterized in that that a ferrous, acid-etchable metal surface is coated. 309882/1076 . - 24 - 3. The method according to claim 1 or 2, characterized in that the chemically deposited, organic / inorganic base coating is applied by an iron-containing or zinc-containing surface with a stable, aqueous dispersion of a base resin, which has a pH of 1.6 to 3 > 8 has and from 0.4 to 5 »^ S simple l'tetrafluoride, calculated as F ~, per liter, 0.3 to 3.0 g of hydrogen peroxide per liter, and ^c j> to 500 g of the dispersed resin per liter , to form the desired basecoat on the surface, and thereafter the coated surface is allowed to dry. 4. The method according to claim 1 or 2, characterized in that the chemically deposited, Applying organic / inorganic base coat by the metal surface with a primer coating composition which disperses a film-forming material, dissolved or emulsified in an acid containing a metal corrosive, an oxidizing agent and a dispersing agent, aqueous phase, for a period of time sufficient to allow the acid to attack the metal surface for the generation of metal ions, which by the oxidizing agent on entry into the aqueous phase with the formation of destabilizing ions are oxidized therein, which make the coating composition unstable and thus the Bringing the coating composition to coagulate, bringing into contact, the stability of the coating composition overall is maintained by: a) continuous or intermittent addition of dispersing agent on the coating composition to achieve a practical match to the build-up of metal ion concentration and or b) by removing metal ions to prevent the build-up of the concentration of metal ions, the effective 309882/1076 Concentration of destabilizing metal ions to not more than 3 g / l "when using the working technique a) alone or in connection with the work technique b) or to no more than 1.5 g / l when used alone the work technique b) is maintained. 5. The method according to claim Λ or 2, characterized in that the chemically deposited, organic / inorganic base coating is applied to an iron-like metal surface by the surface for a period of time necessary to form a coating of the desired thickness with an aqueous, coating-forming composition which contains a dispersion of a water-dispersible base resin in an acidic, aqueous phase, which has a pH value within the range from 1.6 to 5> 0 and which from the start contains at least a noticeable amount of iron ( m) ions, and the surface coated in this way is then rinsed and dried. 6. The method according to claim 1 or 2, characterized in that the chemically deposited, organic / inorganic Applies primer to the surface of an acid-etchable metal, by bringing the metal surface into contact with a composition forming a coating, which contain a film-forming material in an aqueous acid, a metal corrosive and an oxidizing agent Phase comprises, and in that the coating thus deposited on the metal surface is then treated with a solution for rinsing, which contains hexavalent chromium, is rinsed. 309882/1076 7. The method according to claim 1 or 2, characterized in that the chemically deposited, organic / inorganic primer on cie surface a metal accessible to acid etching is applied by coating the surface with a coating composition, which the film-forming material dissolved, dispersed or emulsified in an aqueous, a Metal corrosive acid-containing phase for a sufficient period of time to allow the acid to attack the Metal surface with generation of metal ions, which in the aqueous phase with generation of a layer of the film-forming en, from the coating composition;.;.:. before id and en Material entering on the metal surface, is brought into contact, the stability of the coating composition by bringing them into contact with an ion exchange material is maintained, which is building up the concentration of metal ions in the composition prevented altogether up to a height which the composition as a whole with the effect of flocculation, coagulation, Would destabilize gel formation or the like. 8. The method according to any one of the preceding claims, characterized in that one is a quick-drying Coating applies, which at least one between the two undersides and comprises a topsheet. 9. The method according to any one of the preceding claims, characterized in that at least one de.r quick-drying coatings on the metal surface provided with the base coating as a coating or applying resin powder constituting the film. 309882/1076 10. The method according to any one of the preceding claims, characterized characterized in that at least one of the quick-drying coatings is applied to the base coat applied metal surface as paint, 11. The method according to any one of the preceding claims, characterized in that the chemically deposited, Apply organic / inorganic base coat in a thickness of 0.0025 mm to 0.038 mm. 12. The method according to any one of the preceding claims, "thereby characterized in that the intermediate sub-layer optionally present in a thickness of 0.0025 mm to 0.038 mm and the final top layer in a thickness of 0.018 mm to 0.076 mm. 13 · Objects with a metal surface, characterized by having a composite resin coating wear, which is produced by the method according to any one of the preceding claims. 309S82 / 1076