DE1196467B - Process for the production of oxalate coatings of increased thickness on metals - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. α .:

Number:
File number:
Registration date:
Display day:

C23f

German class: 48 dl - 7/18

1196467
F33357VIb / 48dl

March 7, 1961

July 8, 1965

It is known that the layer weight of phosphate coatings in the production with the help of Solutions of layer-forming phosphates, which have a pH of 1.9 to 3.5, by adding Can increase chelating or complexing organic agents to acidic phosphate solutions. As such effective substances are in particular «-amino acids ^ and polycarboxy-a-amino acids, for example Ethylenediaminetetraacetic acid, called.

When applying oxalate coatings to metal "> surfaces causes the presence of such chelating or complexing agents in the usual oxalization solutions on the other hand, no change in the weight or the thickness of these oxalate layers.

There has now been a process for producing oxalate coatings of increased layer thickness on metals found that works with solutions of special composition. These solutions according to the invention contain in a manner known per se oxalic acid, one or more oxidizing accelerators, an incorporation salt, for example iron salt or trioxalatochrome (III) potassium, optionally activators, Phosphates and / or acetates, and additionally according to the invention polyvinylphosphonic acid and / or a water-soluble copolymer of an alkene phosphonic acid with a monounsaturated or polyunsaturated one organic compound.

Copolymers of vinylphosphonic acid with acrylic acid, methacrylic acid are preferably used or their esters, amides and nitriles and vinyl esters, maleic anhydride or crotonic acid in Consideration.

With the help of the solutions proposed according to the invention. succeeds, - to produce layers, whose <^ thickness is significantly greater than those produced with the known solutions layers..

Polymer concentrations of about 0.3 g / l to about 17 g / l, preferably 0.7 g / l, are particularly useful up to 12 g / l, proven in the oxalation solutions.

The coatings applied using the method proposed according to the invention can be used in many ways Way to be used. While for example on iron or steel wires by means of the conventional Oxalate coatings applied to the metal during deformation In particular, if they are drawn through nozzles several times, they are not able to protect, according to the invention Oxalate layers produced on the wires even for the high demands made by those with few Trains achieved high cross-sectional reductions are made to be well suited.

If the oxalating solutions are used instead of the processes for producing oxalate coatings
increased layer thickness on metals

Applicant:

Metallgesellschaft Aktiengesellschaft,

Frankfurt / M., Reuterweg 14

Named as inventor:

Dr. Willy Herbst, Hofheim (Taunus);

Dr. Heinz Ludwig, Frankfurt / M.- Sossenheim - -

Homopolymers and / or copolymers of alkene phosphonic acids one or more monomeric alkene phosphonic acids, in particular vinyl phosphonic acid and / or, their acidic derivatives, then no change in the layer thickness compared to the in detect coatings produced by phosphonic acid-free solutions.

The oxalate layers according to the method of the invention can be applied to degreased metal parts, in particular on iron, steel and aluminum surfaces, in the usual way by dipping, flooding or by spraying on the solutions. They are then rinsed with water and dried.

The process according to the invention is explained in detail in the following examples.

Example 1

Car body steel sheets are becoming better known in ..! Way treated with a commercially available, alkaline degreasing agent for 10 minutes at 95 ° C and then rinsed with cold water. You are then 10 minutes in a solution of the following composition submerged:

15 g / l oxalic acid dihydrate,
8 g / l sodium chlorate,
5 g / l iron (II) sulfate heptahydrate.

The solution also contains so much alkali metal phosphate that a pH of 1.9 is established. the Bath temperature is around 18 ° C.

0.8 or 1 or 3 or 15 g / l of polyvinylphosphonic acid are added to different parts of this stock solution added. Further parts of the specified solution are 1 or 4 g / l of a copolymer (A) of the Vinylphosphonic acid with acrylic acid (molar ratio 80:20) and 0.8 g / l or 1.9 g / l of a mixed poly-

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merisates (B) of vinylphosphonic acid with vinyl acetate (molar ratio 80:20) were added.

For comparison, parts of the stock solution, which also contain various amounts of ethylenediaminetetraacetic acid, Contain tetrasodium ethylenediamine tetraacetate, glycine or monomeric vinylphosphonic acid.

The sheets oxalized with these solutions are rinsed with water and dried with hot air.

The layer thickness of the oxalate coatings is then determined. The results obtained here are compiled in the following table.

Admitted substance concentration
s / i Layer thickness
μ 20th 1.5 Polyvinylphosphonic acid. 0.8 2.2 Polyvinylphosphonic acid. 1 2.5 Polyvinylphosphonic acid. 3 4th Polyvinylphosphonic acid. 15th 9.9 25th Copolymer A 1 2.2 Copolymer A 4th 2.9 Mixed polymer B 0.8 2.1 Mixed polymer B 1.9 3.1 Ethylene diamine tetra 30th acetic acid 3 1.5 Ethylene diamine tetra J acetic acid 9 1.6 Tetrasodium ethylene diamine tetraacetate 1 1.5 35 Tetrasodium ethylene diamine tetraacetate 3 1.4 Tetrasodium ethylene diamine tetraacetate δ 1.2 Glycine 3 1.3 Glycine 9 1.5 Vinyl phosphonic acid 3 1.6 Vinylphosphanic acid ..... 10 1.9

As can be seen from the table, additives cause of monomeric vinylphosphonic acid or of substances that lead to an increase in the layer weight during phosphating Oxalization means a change in the layer thickness.

Example 2

In the manner indicated in Example 1, car body steel panels are degreased, rinsed and at Room temperature with an adherent oxalate layer Mistake. The oxalation solution used for this purpose has the following composition:

4 g / l oxalic acid dihydrate,
2 g / l sodium chlorate,
1 g / l K ₃ [Cr (C ₂ O ₄ ) ,,].

The oxalized sheets are rinsed with water and dried with hot air. After a dive of 8 minutes, the layer thickness is 1.4 μ. If 1 g / l polyvinylphosphonic acid is used in the oxalating solution described to, layers with a thickness of 2.8 μ are obtained for the same treatment time.

Claims (4)

Patent claims: 1. Process for the production of oxalate coatings of increased layer thickness on metals by means of solutions, the oxalic acid, one or more oxidizing accelerators, an incorporation salt, optionally Contain activators, phosphates and / or acetates, characterized in that that one uses solutions that also contain polyvinylphosphonic acid and / or a water-soluble Copolymer of an alkene phosphonic acid with a mono- or polyunsaturated one contain organic compound. 2. The method according to claim 1, characterized in that one uses solutions that together with polyvinylphosphonic acid or alone a water-soluble copolymer of vinylphosphonic acid with acrylic acid, methacrylic acid or their esters, amides, nitriles or vinyl esters, Contain maleic anhydride or crotonic acid. 3. The method according to claim 1 and 2, characterized in that solutions are used which contain 0.3 to 17 g / l, preferably 0.7 to 12 g / l, of polymer. 4. Solution for the production of oxalate coatings of increased layer thickness on metals, the oxalic acid, one or more oxidizing accelerators, an incorporation salt, optionally activators, Contains phosphates and / or acetates, characterized by an additional content of polyvinylphosphonic acid and / or a water-soluble copolymer of an alkene phosphonic acid with a mono- or polyunsaturated organic compound. Considered publications:
French patent specification no. 1 174045. 509599/396 6.65 © Bundesdruckerei Berlin