JP3256339B2 - Black steel sheet excellent in workability and weldability and method for producing the same - Google Patents

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 excellent in workability and weldability suitable as a material for fields such as automobiles, home appliances, and building materials, and a method for producing the same.

[0002]

2. Description of the Related Art A blackened steel sheet used for automobiles, home appliances, building materials and the like is disclosed in Japanese Patent Application Laid-Open No. 2-217480, which discloses a transparent organic resin film for protecting a colored film after the blackening treatment. As described above, an organic resin film to which a coloring pigment is added is applied to several μm. In order to obtain corrosion resistance, a chromate treatment is performed before coating the resin, or chromic acid is contained in the resin.

[0003] The steel plate manufactured in this way has a beautiful black appearance, but if the user actually performs processing such as punching and bending, and further drawing, the galling occurs and the steel sheet is processed without being completely drawn. In many cases, problems such as cracking of the steel plate occurred during the process.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to solve these problems and to provide a black steel sheet excellent in workability and weldability, and a method for producing the same.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a water-dispersed Zn-Ni alloy coated steel sheet having an anodized black film.
Acrylic resin solution with average particle size of 0.5 to 10μ
m polyolefin wax and chromic acid added
Aqueous solution is coated on anodic electrolytic Zn-Ni alloy plated steel sheet.
Cloth and dried at a plate temperature of 80-150 ° C, and polyolefin wax was added to 100 parts by weight of the formed acrylic resin.
A black steel sheet excellent in workability and weldability characterized by having an organic resin composite film having a thickness of 0.5 to 2 μm containing 1 to 20 parts by weight and chromic acid of 0.2 to 1.0 part by weight, and the present invention also provides: The average particle diameter is 0.5 to 10 based on 100 parts by weight of the nonvolatile content of the solution comprising the water-dispersed acrylic resin.
An aqueous solution containing 1 to 20 parts by weight of a polyolefin wax of 1 to 20 parts by weight and 0.2 to 1.0 parts by weight of chromic acid was applied on a Zn-Ni alloy-plated steel plate subjected to anodic electrolysis, and the reached plate temperature of 80 to
This is a method for producing a black steel sheet excellent in workability and weldability , characterized in that an organic resin composite film having a thickness of 0.5 to 2 μm is formed by drying at 150 ° C.

The anodic electrolytic treatment of a Zn—Ni alloy plated steel sheet
Normal anodic electrolysis may be performed in a chlorate solution.

[0007]

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

The addition amount of the polyolefin wax is 1 to 20 parts by weight based on 100 parts by weight of the solid content of the base resin.
If the amount is less than 1 part by weight, there is no effect on workability. If the amount is more than 20 parts by weight, powdering tends to occur during molding, and it is not preferable because it adheres to a 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 coating, 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, the chromic acid is further added at 0.2 to 1.0.
Add by weight. If it is less than 0.2 parts by weight, corrosion resistance is insufficient,
Exceeding 1.0 part by weight is not preferable because it causes disadvantages such as loss of conductivity and spot welding and loss of grounding. The solution having the above composition is applied on a Zn—Ni alloy plated steel sheet after the anodic electrolytic treatment by a roll coater or the like, and dried at a reached sheet temperature of 80 to 150 ° C. If the temperature is lower than 80 ° C., the drying is insufficient and the adhesion is deteriorated. If the temperature exceeds 150 ° C., deterioration of the resin is accelerated, which is not preferable.

[0010] Such a resin film is formed to a thickness of 0.5 to 2 µm. If the thickness is less than 0.5 μm, a beautiful appearance cannot be obtained.
On the other hand, if it exceeds 2 μm, not only nuggets are not formed when spot welding is performed, but also powdering is liable to occur, which is not preferable in view of workability. Hereinafter, effects of the present invention will be described 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 plate steel plate equivalent to SPCC, plate thickness 0.7mm)
O ₃ 50 g / l, Na ₂ SO ₄ 100 g / l, pH 1.5, a blackening treatment solution of 50 ° C., subjected to anodic electrolysis under the conditions of 75 A / dm ² , 150 C / dm ² It was subjected to resin skin covering. L value before resin coating = 8, G value = 0.5. 2. Resin coating 3966AX (trade name) manufactured by Nippon Parkerizing Co., Ltd. was used as the water-dispersed acrylic resin. The polyolefin wax is manufactured by Sannopco, Sanyo Chemical Co., Ltd.
Manufactured by Asahi Kasei Corporation.

Table 1 shows Examples, Comparative Examples, and corrosion resistance, weldability and workability. Corrosion resistance is measured by salt spray test (JIS Z2
371), based on a white rust occurrence rate of 5% after 200 hours. Weldability is 7.5k with 150kg 40R R type Cu-Cr electrode
The evaluation was made based on whether or not a nugget was formed when the current of A was passed when the current was passed.

Of the workability, the drawability is determined by pressing a non-oiled test piece with a cylindrical deep drawing tester using a wrinkle holding pressure of 1.0 kg, a punch diameter of 33 mm,
Processing was performed at a drawing ratio of 2.18, and the presence of cracks was evaluated. On the other hand, the powdering property was evaluated based on 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 significantly improves the productivity of home appliances, building materials, and automotive products.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI C25D 11/34 303 C25D 11/34 303 (56) References JP-A-4-313368 (JP, A) JP-A-2-217480 (JP, A) JP-A-3-219086 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 15/08 B05D ⁷ /14-7/18

Claims (2)

(57) [Claims] 1. A solution comprising an aqueous dispersion type acrylic resin on a surface of a Zn—Ni alloy plated steel sheet having an anodized black film.
In addition, a polyolefin wax having an average particle size of 0.5 to 10 μm
Anodized electrolytic solution of chromium and chromic acid
Apply on Zn-Ni alloy plated steel plate, reach plate temperature 80 ~ 150 ℃
Characterized by having a 0.5 to 2 μm thick organic resin composite film containing 1 to 20 parts by weight of polyolefin wax and 0.2 to 1.0 parts by weight of chromic acid based on 100 parts by weight of acrylic resin formed by drying with Processability and melting
Black steel plate with excellent contact . 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 comprising an aqueous dispersion type acrylic resin.
An aqueous solution containing 1 to 20 parts by weight of a polyolefin wax and 0.2 to 1.0 parts by weight of chromic acid was applied onto a Zn-Ni alloy-plated steel plate that had been subjected to anodic electrolysis, and the reached plate temperature was 80 to 150.
A method for producing a black steel sheet having excellent workability and weldability , characterized by forming an organic resin composite film having a thickness of 0.5 to 2 μm by drying at a temperature of 400 ° C.