JPH0740501A - Black steel panel excellent in processability and production thereof - Google Patents

Abstract

PURPOSE:To obtain a black steel panel excellent in processability by forming an org. resin composite film composed of an acrylic resin containing a specific amt. of polyolefin wax and a specific amt. of chromic acid and having a specific thickness on the surface of a Zn-Ni alloy plated steel panel having an anodic oxidation black film. CONSTITUTION:A soln. containing an acrylic resin, polyolefin wax and chromic acid is applied to the surface of a Zn-Ni alloy plated steel panel having an anodic oxidation black film and the coated steel panel is dried to form an org. resin composite film. Polyolefin wax has an average particle size of 0.5-10mum and 1-20 pts.wt. of polyolefin wax is added to 100 pts.wt. of the acrylic resin and 0.2-1.0 pts.wt. of chromic acid is further added to 100 pts.wt. of the acrylic resin. The soln. of this compsn. is applied to the Zn-Ni alloy plated steel panel subjected to anodic electrolytic treatment by a roll coater and the coated steel panel is dried at a reaching panel temp. of 80-150 deg.C. By this method, the org. composite resin film with a thickness of 0.5-2mum is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a black steel sheet having excellent workability, which is suitable as a material in the fields of automobiles, home appliances, building materials and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Blackening-treated steel sheets used in automobiles, home appliances, building materials, etc. are disclosed in JP-A-2-217480 with a transparent organic resin film for protecting the colored film after the blackening treatment. As shown in the above, an organic resin film with a color pigment added is applied to a thickness of several μm. Further, in order to obtain corrosion resistance, chromate treatment is performed before coating the resin, or chromic acid is contained in the resin.

The steel sheet produced in this way has a beautiful black appearance, but if the user actually punches it, bends it, and further squeezes it, it will cause galling or will not be drawn completely. In many cases, problems such as cracking of the steel plate occurred during the process.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve these problems and to provide a black steel sheet having excellent workability and a method for producing the same.

[0005]

Means for Solving the Problems The present invention is to apply 1 to 20 parts of a polyolefin wax to 100 parts by weight of an acrylic resin on the surface of a Zn-Ni alloy plated steel sheet having an anodized black film.
Thickness of 0.2 to 1.0 parts by weight and chromic acid
It is a black steel sheet excellent in workability characterized by having an organic resin composite film of 0.5 to 2 μm, and the present invention is a non-volatile content of 100 parts by weight of a solution composed of a water-dispersible acrylic resin, and an average particle An aqueous solution containing 1 to 20 parts by weight of a polyolefin wax with a diameter of 0.5 to 10 μm and 0.2 to 1.0 parts by weight of chromic acid was applied onto anodically electrolyzed Zn-Ni alloy-plated steel sheet, and the ultimate temperature reached 80 to 150 ° C. Dried,
A method for producing a black steel sheet having excellent workability, characterized in that an organic resin composite film having a thickness of 0.5 to 2 μm is formed.

The anodic electrolytic treatment of Zn-Ni alloy plated steel sheet is
The usual anodic electrolytic treatment may be performed in the chlorate solution.

[0007]

The present inventors have found that by adding a polyolefin wax to the resin, it is possible to secure properties with excellent processability. The average particle size of polyolefin wax was limited to 0.5-10 μm because it was 0.5 μm.
If it is less than 10 μm, there is no effect on the workability, and if it exceeds 10 μm, the water dispersibility is poor and sedimentation tends to occur, which is not preferable.

The amount of the polyolefin wax added is 1 to 20 parts by weight based on 100 parts by weight of the solid content of the base resin.
If it is less than 1 part by weight, there is no effect on the workability, and if it exceeds 20 parts by weight, powdering tends to occur during molding, and it is not preferable because it may adhere to the mold. The water-dispersible acrylic resin of the base resin is not particularly specified, but the emulsifier used for water dispersion does not adversely affect the corrosion resistance after painting, or the resin is added when chromic acid is added. It is necessary to select a material that does not have a bad effect such as solidification or film coating.

In the present invention, chromic acid is further added to 0.2 to 1.0.
Add parts by weight. If less than 0.2 parts by weight, the corrosion resistance is insufficient,
If it exceeds 1.0 part by weight, the conductivity is lost, spot welding cannot be performed, and the grounding property is lost, which is not preferable. The solution having the above composition is applied on a Zn-Ni alloy-plated steel sheet after anodic electrolysis with a roll coater or the like, and dried at an ultimate plate temperature of 80 to 150 ° C. If the temperature is less than 80 ° C, the drying will be insufficient and the adhesion will deteriorate. On the other hand, if the temperature exceeds 150 ° C, deterioration of the resin is accelerated, which is not preferable.

Such a resin film is formed to a thickness of 0.5 to 2 μm. If it is less than 0.5 μm, it will not have a beautiful appearance.
If it exceeds 2 μm, not only the nugget is not formed when spot welding is performed, but also powdering is likely to occur, which is not preferable in terms of workability. The effects of the present invention will be described below with reference to examples.

[0011]

【Example】

1, blackening treatment Zn-Ni alloy plated steel sheet (coating weight 20 g / m ^2, Ni content 12
%, Base steel plate SPCC equivalent plate thickness 0.7 mm), NaCl
O ₃ 50 g / l, Na ₂ SO ₄ 100 g / l, pH 1.5, 50 ° C. blackening treatment liquid was blackened by anodic electrolysis under the conditions of 75 A / dm ² and 150 C / dm ^2. It was subjected to resin covering. The L value before covering with the resin was 8, and the G value was 0.5. 2. Resin coating As the water-dispersible acrylic resin, 3966AX (trade name) manufactured by Nippon Parkerizing Co., Ltd. was used. The polyolefin wax is manufactured by San Nopco Co., Ltd., Sanyo Kasei Co., Ltd.
Manufactured by Asahi Kasei Co., Ltd. were used.

Table 1 shows examples, comparative examples, corrosion resistance, weldability and workability. Corrosion resistance is based on salt spray test (JIS Z2
371) and based on the white rust occurrence rate of 5% after 200 hours. Weldability is 7.5k with R-type Cu-Cr electrode with pressure of 150Kg 40R
When a current of A was passed, it was evaluated by whether or not it was energized and a nugget was formed.

Of the workability, the drawability is an oil-free test piece with a cylindrical deep-drawing tester, wrinkle holding pressure 1.0 kg, punch diameter 33 mm,
The film was processed at a drawing ratio of 2.18, and the presence or absence of cracks was evaluated, while the powdering property was evaluated by the presence or absence of peeling of the resin on the wall surface at that time.

[0014]

[Table 1]

[0015]

As described above, according to the present invention, workability is remarkably improved, and corrosion resistance and weldability are not impaired.
This will significantly improve the productivity of home appliances, building materials, and automobile parts.

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location C25D 11/34 303

Claims (2)

[Claims] 1. On the surface of a Zn-Ni alloy plated steel sheet having an anodized black coating, 1 to 20 parts by weight of polyolefin wax and chromic acid are added to 100 parts by weight of an acrylic resin.
A black steel sheet with excellent workability, characterized by having an organic resin composite coating of 0.2 to 1.0 parts by weight and a thickness of 0.5 to 2 μm. 2. An average particle diameter of 0.5 to 10 μm with respect to 100 parts by weight of a nonvolatile content of a solution composed of an aqueous dispersion type acrylic resin.
1 to 20 parts by weight of the polyolefin wax and 0.2 to 1.0 parts by weight of chromic acid are applied to the anodically-electrolyzed Zn-Ni alloy plated steel sheet, and the ultimate plate temperature reaches 80 to 150
A method for producing a black steel sheet having excellent workability, characterized by forming an organic resin composite film having a thickness of 0.5 to 2 μm by drying treatment at ℃.