JPH04505479A - Method for forming a manganese-containing phosphate film on metal surfaces - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] A method for forming a manganese-containing phosphate film on a metal surface. of steel, galvanized steel, aluminum and/or their alloys. The present invention relates to a method for forming a manganese-containing phosphate film on a surface.

Automotive bodies, auto accessories and spare parts, agricultural machinery, refrigerators, and more Products such as small parts of Phosphate treated by lead process and then mostly electrophoretically dip coated.

Such manganese-modified zinc phosphate coatings as primers for modern painting equipment are , for example, Roland (W, A, Roland) and Gottwald (K, -H, Gottwald), Metalover Frey (Metallover) fljiche), known from June 1988. Here, low zinc phosphate treatment The use of manganese ions in addition to zinc and nickel in the process Significantly improved corrosion protection properties result, especially when surface-modified metal sheets are used. It is discussed. Adding manganese to zinc phosphate film improved alkali resistance. Finer and denser crystals can be obtained. At the same time, the useful range of phosphating baths has expanded, Phosphating aluminum in combination with steel and galvanized steel By doing so, it is possible to form layers while still maintaining the quality standards normally achieved. Ru.

Such composites comprising various metals such as aluminum and steel BACKGROUND OF THE INVENTION Material parts are now being used more frequently in automobile manufacturing.

From European Patent Application No. 0 261 704, a homogeneous material with a high degree of coverage At least one accelerator in addition to zinc and phosphate to form a phosphate layer and a phosphate treatment that must contain exactly the amount of fluoride ion that must be maintained. A phosphate film is formed on the surface using a solution spray or spray dipping method. There are known ways to do this. Additionally, European Patent Application Publication No. 0261704 , the amount of free acid (FS) must be adjusted according to the formula described therein do not have.

In contrast, the purpose of the present invention is to obtain a more uniform phosphate film and to improve the phosphate treatment technology. Steel, galvanized steel, aluminum and/or To provide an improved method for forming phosphate films on the surfaces of these alloys. It's there.

The above purpose is Zn"　0.8~1.4g/C Mn"　0.6~2.C)g/I2 and as a phosphate adhesion promoter, NO, -0.04~0.12g/Q CffO30.6~2.0g/C and/or An aqueous solution containing sodium 3-nitrobenzene sulfonate, the free acid content being is adjusted to 1.4 to 1.8 points and the total acid content is 18 to 30. steel, galvanized steel, by spraying or spray dipping using of aluminum and/or their alloys or aluminum-steel composites This is achieved by forming a manganese-containing phosphate film on the surface.

In conventional low zinc treatment, the free acid content should be approximately 0.6 to 0.9 points. It has been known. Higher values result in less uniformity on the surface treated in this way. A thick discontinuous phosphate layer is formed and rust formation on the steel surface is also observed.

In fluoride-based phosphate treatment baths, the addition of manganese can be used without the above disadvantages. Basically increases the free acid content.

The use of manganese in the phosphate layer has various advantages in the base layer described above. What do you do?

The present invention provides a relatively It has been shown that optically uniform phosphate layers can be obtained using small amounts of fluoride. It was.

In the surface treatment of steel, phosphophyllite or manganese-containing phosphophyllite Proven low zinc technology for light formation can be maintained while improving quality Zinc content can be increased without decreasing it.

Galvanized steel sheet, alloyed steel sheet and aluminum surface Improved results were obtained using manganese, and at the same time the manganese layer Increased zinc content in subsequent coatings by electrophoretic electrodip coating due to contamination with do. According to the present invention, the interaction of manganese and zinc content in phosphating solutions was discovered.

Aluminum materials treated by the method of the invention include pure metals and alloys thereof. . Namely, by way of example, high quality aluminum, AlMg and AlMg5j processing Materials can be listed. Further examples of these aluminum materials include, for example: Aluminium-Taschenbu ch) J, 14th edition, A luminium- V erlag), Düsseldorf, 1983. The method of the invention The more processed steel is used especially for automotive bodywork, automotive accessories and spare parts. production such as agricultural machinery, refrigerators and small parts usually used in sheet form. Including products. The term "galvanized steel" refers to electrolytic deposited and hot dip applied refers to zinc and known zinc alloys.

When carrying out the process of the invention in spray immersion mode, the spray time is approximately equal to that of a continuous phosphate layer. The time must be such as to ensure formation.

Modern all-immersion plants are characterized by a large number of consecutive steps. [Full immersion plant (f The term ul im + ner sion plant) J is applied by dip application. Derived from phosphate treatment. In a separate process step, a spraying operation is also carried out and the substrate is Post-sprayed upon exiting the immersion bath. Important to the best phosphatizing process are other activities. It is a sexualization process. The layer to be phosphated, which is pre-cleaned and activated, is usually , cleaned, rinsed and subsequently activated prior to the phosphating operation. Here, an example For example, an aqueous suspension containing titanium phosphate can be used.

Maintaining the concentration range according to claim 1 provides a high quality, i.e. uniform, phosphate coating. This is an essential condition for forming a film. When the value is lower than the indicated concentration range, The layers become uneven. In particular, the layer becomes less suitable for subsequent electrodip coating.

The above fluoride concentration according to the present invention is determined by a special ion-sensing method in a buffer solution of pH 5.3. It is measured using a sex electrode. That is, these values indicate that the fluoride concentration is It is not comparable to the values stated in the prior art that are measured directly in a physical solution.

In a preferred embodiment, the invention comprises: Nit'' 0.3~0.8g/Q It is characterized by using an aqueous solution containing the following.

The surface coated by the method described above is then coated with a paint electrodip coater known in the art. Can be used in law. Accordingly, one further aspect of the invention is to using a surface preparation method for air dip coating.

The invention is further illustrated by the following examples.

Example 1 Cleaning, rinsing, (activation) phosphate treatment, rinsing, post-passivation, in fully desalinated water In a customary continuous process including a rinsing step, three compositions A, B and Conversion coating (convers 1on-coat) according to the following bath conditions corresponding to C. 〇Appropriate method for performing the process Bath parameters (A) Spray (B) Spray (C) Spray immersion "Total acid J 26.5 26.3 22.2Zn" (g/12) 0.9 0.9 1.0Mn" (g /12) 0.9 0.6 Ni″″(g/I2) 0.7 0.7 0.7POa″-(g/12) 20 ．． 5 20.2 17.1 CI20'-(g/2) 0.95 0.95-F -(ppm) * 380 380 400 Temperature ("C) 58 58 58 Time (seconds) 120 120 180 Note) *: Measured using an ion-sensitive electrode in a buffer solution of pH 5.3 **: Sodium nitrite Phosphophyllite and/or manganese-containing phosphophyllite in steel In order to form It was possible to increase the zinc content without any problem.

In galvanized, alloyed steel sheet and aluminum, Due to manganese contamination, the next step using KET primer (see Example 2) A clear identifiability of the corrosion resistance obtained in the application of the above was ensured.

After applying process A to the individual substrates according to DIN 50942, the When measuring the mass, the following measured values (average values) were obtained Steel St 1405 2. Og/12 steel, electrogalvanized 2.4g/f aluminum (A( 2Mg0.43i1.2) 2.8g/Q aluminum (AQMg4.5Mn) 2.7g/+70 The manganese content of the phosphate layer was measured by atomic absorption spectroscopy (A ) determined quantitatively (average value) Steel st 1405 6.4% Steel, electrogalvanized 4.7% Aluminum (ACMgo, 4Si1.2) 6.2%.

No new characteristic bands were found in the manganese-containing phosphate layer by X-ray diffraction. won.

Example 2 According to the VDA changing climate test (VDA test procedure 621 415), the following The corrosion resistance of phosphate coatings was measured on different substrates. Standard electrical after coating application Electrophoretic dip coating composition [BAS F Fa rben und Lacke)'s KET-Primer ) FT 85 70421) was used.

The test period for the VDA changing climate test was 5 to 10 cycles. During this period, The treated substrate was exposed to a condensate changing climate according to DIN 50017. Furthermore, the base material according to DIN 50014 for a certain period of time at room temperature (18-28°C) during the test period. Stored. Furthermore, in the above-mentioned changing climate test, salt water according to DIN 50021 A spray test was conducted.

At the end of the test cycle, the following data were obtained.

A. Phosphate treatment solution containing manganese Base material 10 cycles 20 cycles Subpaint penetration in subsequent cuts mm mm Steel 5t1405 0.6~0.8-Steel, electrogalvanized 2.0~ 2.5-aluminum (A12Mg0.4Si1.2) -0,2 aluminum (no fluoride) up to 10 B, Manganese-free phosphate treatment solution (comparison) base material 10 cycles 20 cycles Subpaint penetration in subsequent cuts mm man Steel St 1405 o. 9~1.2-Steel, electrogalvanized 3.4 ~4.0-aluminum (AQMgo, 4Si1.2) -0,8~1.0 Al Minium (fluoride free) up to 1O international search report □□, PCT/RP 90100B42 International Search Report EP 9000842 S^　37158

Claims (4)

[Claims] 1. Zn2+0.8~1.4g/l Mn2+0.6~2.0g/l Ni2+0.3~14g/l PO43-10~25g/l NO3-2~10g/l F-0.2~1.0g/l and as a phosphate adhesion promoter, NO2-0.04~0.12g/l ClO3-0.6-2.0g/l and/or Sodium 3-nitrobenzenesulfonate 0.2-1.0g/l is an aqueous solution containing , and the free acid content is adjusted to 1.4 to 1.8 points. By spraying or spray dipping with an aqueous solution with a total acid content of 18-30 , steel, galvanized steel, aluminum and/or their alloys; is a method for forming a manganese-containing phosphate film on the surface of aluminum steel composite materials. Law. 2. Zn2+0.8~1.0g/l Mn2+0.8~1.2g/l Ni2+0.3~0.8g/l PO43-14~20g/l NO3-3~6g/l F-0.3~0.6g/l 2. The method according to claim 1, wherein an aqueous solution containing the following is used. 3. Claim 1 or 2, wherein a phosphate film is formed on the aluminum steel composite material. Method described. 4. The method according to any one of claims 1 to 3 for forming a surface for electrodip coating of paint. Using the methods described.