DE3408573A1 - METHOD FOR TREATING METAL SURFACES - Google Patents

Description

NIHON PARKERIZING CO., LTD. 3 March 7, 1984

Tokyo 103, Japan DROZ / LWÜ / 1590P

Prov. No. 9141 M.

Process for treating metal surfaces

The invention relates to a method for treating possibly provided with a chemical conversion coating Metal surfaces by bringing them into contact with an aqueous solution containing reactive organosilane, and then Drying up the solution.

It is known to apply protective coatings to metal surfaces, to improve the corrosion resistance and the adhesion of a subsequently applied paint. To do this will be Usually the metal surfaces are brought into contact with solutions that have a phosphate coating and / or metal oxide coating form. Protective coatings with a similar effect can also be combined with solutions based on oxalate ions, chromate ions and the like. be generated.

The generation of the so-called Umwandlungsüberzuge takes place in the general according to the procedural scheme

Cleaning,

Water flush,

Formation of conversion coatings,

Water flush.

To further improve the conversion coating obtained in this way it is common to start treatment with an after-treatment

solution solution. For this purpose, solutions based on chromate are used in particular. Although this form of follow-up treatment is quite effective, as a result of the toxicity of the chromate solutions, which special precautions are taken when using Application makes it necessary, and the wastewater problems increasingly a move away from such aftertreatment solutions recognizable. It can also have an impact on the formation of conversion coatings on container material for food and beverages the contents of the container cannot be excluded.

In the aftertreatment of conversion coatings, it is known to use a discontinuous sealing layer hydrophobizing agent, e.g. using organic substances, e.g. resin condensation products modified on the basis of polyisocyanate (DE-AS 11 47 820) to produce or to seal with drying oils or low-viscosity paints (H. Fortmann "Post-treatment process for phosphated iron parts", metal goods industry and electroplating MSV No. 6 (1943), Page 229). However, these means could be lower than the chromium-containing aftertreatment solutions for reasons Quality does not enforce. In addition, many of these agents did not produce useful results.

A conversion coating, in particular phosphate coatings, also chemically applied for post-treatment The method provides for using solutions which contain a certain poly-4-vinylphenol compound (DE-OS 31 46 265).

The pH value of the solution used is usually in the alkaline range, which is the case when treating with Metal surfaces provided with conversion coatings may have the disadvantage of partial delamination can be.

With another polyvinylphenol compound substituted in a certain way can be both metallic surfaces

as well as those that were previously provided with a conversion coating have been treated (EP-OS 91 166).

Finally, it is known that organosilanes can be used as adhesion promoters for producing well-adhering coatings on metal surfaces or to use metal surfaces previously provided with a conversion coating (Ulimann, Encyklopadie der techn. Chemie, 4th Edition, Volume 21, pages 496 ff .; DE-OS 25 43 519). Although the aforementioned way of working with certain Advantages, especially with regard to adhesion, is associated with the disadvantage that the corrosion protection of the so treated and then painted metal surface is not satisfactory.

The object of the invention is to provide a method for treating those which may have been provided with a chemical conversion coating To provide metal surfaces, which additionally improves the corrosion protection of the metal surface in particular and is not associated with any environmental or application problems.

The object is achieved in that the method of the type mentioned at the outset is configured in accordance with the invention in this way that you can optionally with a chemical conversion coating brings metal surfaces into contact with a solution which, in addition to organosilane, also contains titanium and / or contains zirconium fluoride compound.

The term "aqueous solution" includes solutions as Solubilizers contain certain amounts of alcohol or similar water-soluble solvents.

It is particularly advantageous if you have a preferred embodiment of the invention, the metal surfaces optionally provided with a chemical conversion coating with a

Solution that brings an organosilane into contact with at least Contains 2 reactive groups.

Organosilanes suitable for carrying out the process according to the invention are described in Ulimann Ie , in particular in Tables 6 to 8 on pages 499, 501 and 503. Particularly suitable organosilanes are trimethylmethoxysilane, / "- aminopropyltriethoxysilane, ^ - aminopropyltrimethoxysilane, N-ß- (aminoethyl) ^ - aminopropylmethyldiethoxysilane, vinyl triethoxysilane, vir; yltris (ß-inethoxyimethoxy) silane, these substances In the molecule, inorganic substances contain chemically binding reactive groups such as methoxy, ethoxy and silanol groups, as well as organic substances such as plastics, chemically binding reactive groups such as vinyl, epoxy, methacrylic and amino groups.

Particularly suitable titanium or zirconium fluoride compounds are fluorotitanic or hydrofluoric zirconic acid and ammonium fluorotitanate or zirconate. You can optionally in the treatment solution by reaction of e.g. metallic Titanium or zirconium, titanium or zirconium oxide, hydroxide and the like. With hydrofluoric acid, optionally in the presence of Ammonium carbonate.

The solution to be used in the method according to the invention is characterized are characterized by high stability, i.e. no components fail when they are used.

The treatment solution can be applied in any way. Suitable forms of application are e.g. brushing, Spray on, roll up, dip or flood.

The drying temperature can be selected within wide limits and is generally in the range from 60 to 300 ^° C.

With the method according to the invention, in particular Steels, alloy steels, aluminum and zinc and their alloys, steels plated with zinc or tin, or otherwise galvanized or tinned steels are treated. The aforementioned substrates can also be coated beforehand with zinc or iron phosphate layers or chromate layers have been provided. Although those with the method according to the invention on metal surfaces coatings produced a high level of corrosion protection and excellent adhesion properties for the subsequent painting convey, the effect can be increased if the process is used for the aftertreatment of metal surfaces previously provided with a conversion coating.

Preferred embodiments of the invention provide, if necessary Bringing metal surfaces provided with a chemical conversion coating into contact with a solution, the organosilane in a concentration of 0.5 to 100 g / l, preferably from 1 to 50 g / l or the titanium and / or zirconium fluoride compound in a concentration of 0.01 to 5 g / l, preferably in one Concentration from 0.05 to 1 g / l, contains or in which the ratio of organosilane to titanium and / or Zirconium fluoride compound in the range from (10 to 200): 1, preferably from (20 to 100): 1.

Outside of the ranges mentioned, either the solution constituents no longer have a sufficient effect or but no significant increase in the effect can be seen.

Another preferred embodiment of the invention provides, optionally with a chemical conversion coating to bring metal surfaces provided with the solution in such a way that after the subsequent drying of the solution film has a layer weight of 10 to 300 mg / m

is obtained.

Ä 3Λ08573

The invention is illustrated by way of example and in greater detail on the basis of the following examples.

Examples

Four treatment solutions were prepared which were as follows:

Solution 1:

10 g vinyl triethoxysilane 100 g methanol

1 g ammonium hexafluorotitanate.

It was diluted 1 liter with water. The pH of the solution was 4.0.

Solution 2:

5 g methacryloxypropyltrimethoxysilane 20 g ethanol

0.2 g hexafluoro2irconic acid 0.2 g of hexafluorotitanic acid

The mixture mixed with mfct 1 l of water had a pH of 3.0 on.

Solution 3:

30 g of N-ß-CAminoethyDjf ^ aminopropyltrimethoxysilane 3 g ammonium hexafluorotitanate

1 l of water were added. The pH of the solution was 11.0.

Solution 4:

10 g of 3 ^ -aminopropyltriethoxysilane 1 g of hexafluorozirconic acid

1 l of water were added. The pH of the solution obtained was 10.0.

Steel sheets, galvanized steel sheets and aluminum sheets, which had previously been cleaned with an alkaline degreasing agent, were immersed for 5 seconds in the treatment solutions mentioned above, freed from excess solution by squeezing rollers and dried ^{in a hot air stream of 120 ° C. for a period of 30 seconds.}

The coated metal sheets were then provided with an acrylate varnish from 20 to 25 μm thick. The paint was ^{baked at 200 °} C. for 3 minutes.

At the same time, test panels of the same nature were treated with solutions 1 to 4, which were treated with the aforementioned Solutions matched, but did not contain any titanium and / or zirconium fluoride compounds. Type of treatment and painting agreed.

Finally, aluminum sheets that had been cleaned under alkaline conditions were chromated with a 7% strength by weight chromating solution and rinsed with water and treated with acrylate varnish as described above.

The panels were then subjected to various tests.

The salt water spray test was carried out in accordance with JIS z-2317 at to which a cross-cut reaching down to the metal surface was made before the spray treatment. It was time

registered until the cross-notched layer of paint flaked off.

Erichsen checkerboard test: This is where the lacquer layer is notched in 100 chessboard fields of 1 mm each. Then press from the back of the checkerboard squares 3 mm through the surface with the Erichsen tester and stick adhesive tape to the curvature of the paint surface. Then you tear quickly removes the adhesive tape from the lacquer surface and registers the number of checkerboard fields whose lacquer layer was retained.

Erichsen chessboard field test after the lapse of time: Here, the treated metal sheets were initially ^{left to lie for 7 days at 40 °} C., then painted and then subjected to the Erichsen chessboard field test in accordance with the requirements.

The results of the tests are tabulated below. The sheets treated according to the method according to the invention are shown as implementation examples (implementation example), the others referred to as comparative examples (Comp. Ex.). Also, the results are for completely untreated, so only cleaned and varnished sheets indicated.

A comparison of the results of the working and comparative examples shows that the corrosion protection of the sheets treated by the process according to the invention is maintained an optimal paint adhesion is consistently considerably improved.

The only chromated aluminum sheet shows one also excellent corrosion protection, but shows significant deficiencies in the Erichsen checkerboard test.

Tabel

treated
object treatment .E.g. .E.g. 1 salt
water
sprayed Hours. Eric
Schac
field- stole Exec Il It 2 120 Hours. 100 plates Il M. Il 3 120 Hours. 100 Il It ti 4th 140 Hours. 100 Il E.g. E.g. 1 120 Hours. 100 Cf. It ti 2 20th 100 Il It dd 3 20th Hours. 100 It M. It 4th 20th Hours. 100 Il untreated untreated 20th Hours. 100 Exec 1 10 Hours. 10 galvanized Il 2 240 Hours. 100 stole Il 3 240 Hours. 100 plates Il 4th 300 Hours. 100 Cf. 1 240 Hours. 100 Il 2 48 Hours. 100 ti 3 48 Hours. 100 Il 4th 48 Hours. 100 48 Hours. 100 40 20th

n- Erichsen-

Checkerboard checkerboard test
st after the passage of time

treated item

treatment

Salt-Erichsenwasser checkerboard spray test field test

Erichsen-

Checkerboard

field test

after the passage of time

aluminum Exec. 1 plates »1 I! 2 it η 3 1 »Il 4th Cf. E.g. 1 (I ti 2 ι »it 3 It tt 4th ti ti 5 (30 mg / m Chrome) untreated

500 Hours. 100 500 Hours. 100 500 Hours. 100 500 Hours. 100 72 Hours. 100 72 Hours. 100 72 Hours. 100 72 Hours. 100 500 Hours. 100 72 Hours. 30th

100 100 100 100 100 100 100 100 50

20th

Claims (6)

Claims 1. A method for treating metal surfaces optionally provided with a chemical conversion coating by bringing them into contact with an aqueous solution containing reactive organosilane, and then drying the solution, characterized in that the metal surfaces optionally provided with a chemical conversion coating with a Bringing solution into contact, which in addition to organosilane also contains titanium and / or zirconium fluoride compound. 2. The method according to claim 1, characterized in that the metal surfaces optionally provided with a chemical conversion coating are brought into contact with a solution which contains an organosilane with at least two reactive groups. 3. The method according to claim 1 or 2, characterized in that the metal surfaces, optionally provided with a chemical conversion coating, are brought into contact with a solution containing the organosilane in a concentration of 0.5 to 100 g / l, preferably 1 to 50 g / l, contains. 4. The method according to claim 1, 2 or 3, characterized in - net that the metal surfaces optionally provided with a chemical conversion coating with a Solution brings into contact, the titanium and / or zirconium fluoride compound in a concentration of 0.01 to 5 g / l, preferably in a concentration of 0.05 to 1 g / l »contains. 5. The method according to one or more of claims 1 to 4, characterized in that the metal surfaces optionally provided with a chemical conversion coating are brought into contact with a solution in which the ratio of organosilane to titanium and / or zirconium fluoride compound is in the range of ( 10 to 200): 1, preferably from (20 bio 100): 1. 6. The method according to one or more of claims 1 to 5, characterized in that the metal surfaces, optionally provided with a chemical conversion coating, are brought into contact with a solution in such a way that, after the subsequent drying of the solution film 2 layer weight of 10 to 300 mg / m is obtained.