DE2039912B2 - PROCESS FOR THE PRODUCTION OF ADHESIVE ENAMEL LAYERS ON METAL SURFACES - Google Patents

Description

or higher for about 5 to 10 minutes and then can be used immediately or after a long period of storage Enameled almost all common top enamel frits will.

The drainage of the phosphated metal surface is important insofar as considerable disturbances in the enamel layer can be expected without it, since the relatively tightly bound (crystal) water can lead to enameling defects such as "blistering", "pitting" and "pinholes". In general, a good result cannot be expected without dehydration. Dewatering can be advantageously achieved by heating to temperatures above 12O ⁰ C.

It has been found that white and other sensitive colored enamels are particularly favorable according to the invention can be used. The resulting enamel layers are uniform, have a high Gloss and show excellent flexibility, impact resistance and thermal shock resistance. The enamel layer thicknesses can vary depending on the intended use, but are common Enamel layer thicknesses of about 0.10 mm are applied.

ίο According to the method »impact test DIN 51 155« with iron-manganese phosphating, neutralization, drying at 130 ⁰ C - ■ - 15 minutes and direct enameling, the adhesive strength (in kp) was determined with increasing layer weight (mean values):

Layer weight Mn - Fe phosphate Adhesion strength in kp in mg / cm ² (Mean values) (Mean values) 0.00 etv.a 0.15 0.05 0.3 0.10 0.4 0.15 0.5 0.20 1.0 0.25 1.5 0.30 2.4 0.40 3.7 0.5 4.7 0.6 6.3 0.7 8.7 0.8 > 9.0 0.9 > 9.0 1.0 > 9.0 1.1 > 9.0 1.2 7.8 1.3 4.4 1.4 1.4 1.5 0.2 1.6 0.2

It is found that an optimum of adhesive strength lies in the range from 0.6 to 1.2 mg / cm ^2. The values of the adhesive strength drop sharply below and above this range.

A comparison with samples produced according to the known method led to adhesive strengths of only about 5.5 kp.

The present invention
the following advantages:

points in particular

1. High adhesion of the enamel layer;

2. Extensive independence from the metal, especially steel quality;

3. simple technology;

4. low chemical costs;

5. low investment costs.

Claims (5)

such phosphate layers are worked, the layer weight of which does not exceed 580 mg / ft2. According to patent claims: an oxidizing atmosphere is used for phosphating at high temperatures. 1. Process for the production of adhesive enamel 5 As tests have shown, phosphate layers on metal surfaces using layers do not generally have adhesion-promoting properties; marked- phosphate layers separating on the bond enamel - marks that on the pure metal surface metal. The enamel cracks off when it cools down after the manganese or manganese-iron-phosphate-io firing process. A layer with a layer weight of between 0.65 and 1.30 mg / cm ^2, which is required in the United States' method, is applied; ⁰ C, analogous application of this working method,
preferably 145 ° C, dehydrated and then without As has been found, the height of the layer comes the application of a base enamel layer directly 15 weight during the phosphating for the adhesive strength is enameled. the enamel layer is a surprisingly decisive factor 2. The method according to claim 1, characterized in meaning to. In the case of the known method is characterized in that coating weights achieved for phosphating a concentrate, which are too low to achieve a 0.2 to from 11.7 ° / o manganese, 41.6% phosphate, ° / ₀ nitrate optimum adhesive strength. and 46.5 prepared ° / ₀ water of this con- 20 Accordingly, the invention provides a 10 ° / "aqueous solution, the process of centrate prepared, heated for producing adherent metal Emaüschichten This solution to the boil, with iron surfaces using Phosphate layers have a ratio of total acid to free acid = 10 as an adhesion promoter for single-layer enamelling and the pure metal surface is characterized at about 95 ° C in this solution for 5 to 20 minutes by manganese or manganese iron -Phosphating is dipped. a layer with a layer weight between 0.65 3. The method according to claim 1 or 2, characterized and 1.30 mg / cm ^{2 is} applied, the phosphated characterized in that on the phosphated metal surface at over 120, preferably 145 ° C surface a white enamel of a layer thickness of drained and then without the application of an approximately 0.10 mm is applied. 30 base enamel layer is enamelled directly. 4. The method according to any one of claims 1 to 3, the method according to the invention can in particular characterized in that a ferrous metal is advantageously used on steel and iron surfaces is phated. will. 5. The method according to any one of claims 1 to 4, before the actual phosphating is the characterized in that steel is phosphated 35 metal surface one of the known cleaning agents. subject to proceedings, d. i.e., the metal surface becomes degreased and pickled. The pure metal surface will then subjected to one of the conventional manganese or manganese-iron phosphating processes. 40 For the phosphating according to the invention, all Mn or Mn / Fe- The invention relates to a method for producing phosphating solutions. Particularly Adhesive enamel layers on metal surfaces, phosphating is advantageous as follows Use of phosphate layers as adhesion promoters carried out: for single-layer enamelling. 45 First a concentrate of 11.7% manganese, For the preparation adherent to Emaüschichten 41.6 ⁰ ₀ Z phosphate, 0.2 ° / ₀ nitrate and 46.5% water to the Direktemaillierverfahren are made different encryption. This concentrate can drive copper or known, in particular processes in which trace amounts of nickel contain up to 0.1%. A 10% solution in water is deposited from this concentrate in thin layers of nickel on the metal surfaces. It is also known to provide 50. Then the solution is heated to the boil, so-called “adhesive oxides” are placed on the metal surfaces and the so-called acidification ratio is set to 10 using steel wool. According to the method of the German patent specification 340 for the preparation of iron raw material for total acid _ ca _urever [, a | _tn j _s _ ig
the application of a base glaze or a one-off 55 free acid
A phosphate layer dried at 225 ^° C. serves as an adhesive layer. In view of the excessive filtration, the bath is kept sludge-free. The concentration of hydrogen ions is only one In the clear phosphating solution, the cleaned extremely low layer weight is achieved. Metal and immersed at about 95 ° C for 5 to 20 minutes Also in the process according to the USA patent specification 60 grooves phosphated. The resulting layers can 076 869 a phosphate layer will be colored differently depending on the type of metal. at used for single-layer enamelling. Depending on the type of steel, han- steels range from gray to If it is an Fe-phosphating with slight black colorations. Depending on the working conditions Amounts of copper, with the exclusion of air, different layer thicknesses can be applied must become. Here, too, the layers obtained are denatured. A layer weight has proven to be particularly advantageous weights relatively low. between 0.65 and 1.30 mg / cm ² proved. The USA.-Patent 2 809 907 describes the The phosphated metal surface is then Use of phosphate oxide layers, with ßend at a temperature of preferably 145 ° C