JP2971156B2 - Manufacturing method of surface treated steel sheet with excellent adhesion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a surface-treated steel sheet having good adhesion as a base material for bonding a steel sheet to a sheet material such as resin and metal.

[0002]

2. Description of the Related Art In general, steel sheets (laminate steel sheets) in which a sheet-like resin is adhered to a steel sheet with an adhesive are often used for automobiles, home appliances, and building materials. In recent years, since these steel sheets are required to have high corrosion resistance, zinc-based surface-treated steel sheets are used instead of cold-rolled steel sheets. Particularly, an easily available electrogalvanized steel sheet having excellent surface smoothness is often used.

On the other hand, examples of bonding a sheet material such as a metal to a steel sheet include damping steel sheets, steel sheets for printed circuit boards, and the like. There are many.

[0004] When an electrogalvanized steel sheet is used as the adhesive base, a steel sheet subjected to a phosphate treatment (bonding steel sheet) (eg, Japanese Patent Publication No. 58-57511) or a steel sheet subjected to a chromate treatment (chromate steel sheet) ( For example, JP-A-50-14550) is used.

However, these steel sheets do not always have sufficient performance. That is, the bond steel sheet has phosphate crystals formed on the surface, but since it is poor in toughness and weak in deformation, the bonded sheet is peeled off during bending.

[0006] Since the chromate film has a small amount of adhesion, unlike a bond steel plate, it has good adhesion in bending. However, under a high-temperature and high-humidity state of 100 ° C. or more, the adhesiveness is significantly deteriorated.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing a surface-treated steel sheet for an adhesive base, which does not degrade the adhesiveness even at a high temperature of 100 ° C. or higher, which solves the above problems.

[0008]

Although it is not clear why the conventional surface-treated steel sheet is inferior in adhesiveness, the present inventors have found that, particularly when H ₂ O in the chromate film is dehydrated at the time of heating and bonding, gas is generated. It is presumed that oxidation and corrosion of the underlying plating occur, which causes a decrease in adhesion and peeling. Therefore, the inventors of the present invention have conducted intensive studies focusing on the activity of the base plating and the drying conditions of the chromate film, and have reached the present invention.

That is, according to the present invention, a total of 0.05 to 5 g / l of Ni ²⁺ and / or Co ²⁺ is contained on the surface of a steel sheet or a galvanized steel sheet, and Total is contained as an impurity.
The current density is 20 to 20 in an acidic plating bath of pH 1 to 6 in which Fe is limited to 2 g / l or less and Pb is limited to 2 mg / l or less.
0 A / dm ² is applied to the electro-zinc alloy plating, and then immersed in a coating reaction type chromate solution to obtain 0.5 to 1 in terms of Cr.
Provided is a method for producing a surface-treated steel sheet having excellent adhesiveness, characterized in that a chromate film of 20 mg / m ² is formed and then dried at an ambient temperature of 120 ° C. or more and a reached plate temperature of 100 to 300 ° C. Is what you do.

The present invention also provides a water-soluble, water-dispersible or organic solvent-based organic polymer compound as an organic resin film on a surface-treated steel sheet obtained by the above method, in a dry weight of 0.2 to 2. An object of the present invention is to provide a method for producing a surface-treated steel sheet having excellent adhesiveness, characterized in that 0 g / m ^{2 is} adhered.

Hereinafter, the present invention will be described in more detail.

According to the present invention, a steel sheet or a galvanized steel sheet is first coated with a zinc alloy and then subjected to a chromate treatment to produce a surface-treated steel sheet having excellent paint adhesion. Further, an organic resin film is formed on the chromate-treated zinc-based alloy-plated steel sheet thus obtained.
The respective steps and the reasons for the limitations are described below.

(1) Electro-zinc alloy plating treatment In the electro-zinc alloy plating treatment of the present invention, a zinc alloy plating surface which is less susceptible to oxidation is produced by controlling the amount of trace components in the zinc alloy plating bath. The steel sheet to be treated is a steel sheet or a galvanized steel sheet. When using the latter, use a steel plate pre-galvanized on a separate line, or, on an electroplating line with multiple cells, perform zinc-based plating on the first few cells and continue with at least the last cell. The above alloy plating may be applied. Zinc plating includes zinc plating.

Ni ²⁺ and / or Co ^{2+ in} plating bath
If the total amount is less than 0.05 g / l, the plating surface is active and extremely susceptible to oxidation, and if it exceeds 5 g / l, the surface turns black and impairs the galvanized appearance, so it is limited to 0.05 to 5 g / l.

[0015] Total Fe is the total sum of Fe ²⁺ and Fe ³⁺ ions. Since the plating bath, Fe ²⁺ is easily oxidized to Fe ^3+, Fe ^2+, and Fe ^3+, to control, respectively, is extremely difficult, Total
It is realistic to manage with Fe. Fe ²⁺ , Fe
^{For 3+} , Fe ³⁺ has a greater effect, but Fe ²⁺ also has an effect, and there is no particular problem even if it is managed by Total Fe. To
When tal Fe exceeds 2 g / l, the zinc surface becomes more susceptible to oxidation.

Although the lower limit is not particularly limited, iron is inevitably contained in the plating bath due to dissolution of the steel sheet, and it is practically extremely difficult to reduce it to zero. For removing iron ions, various kinds of chelating resins and the like can be used.

If Pb exceeds 2 mg / l, it is also susceptible to oxidation. This has a large effect even if the potential difference between Zn and Pb is large and very small. The lower limit is not particularly limited, but Pb exists as an impurity of Zn, and it is practically extremely difficult to set it to zero. B for removal of Pb
A method of adding aCO ₃ into a bath is common.

The basic zinc alloy plating bath may be any bath such as a sulfuric acid bath or a chloride bath, and may be any electroless zinc alloy plating having a good appearance with a pH of 1 to 6 and a current density of 20 to 200 A / dm ² .

With respect to the amount of zinc plating, if the basis weight is large, the corrosion resistance is improved in proportion thereto, but taking into account the increase in cost due to the increase in the basis weight, 5 to 60 g / m ^2.
Is appropriate. The plating in the bath in which the trace components are controlled as described above may be performed on the entire plating layer, but only the outermost layer of the plating layer is 0.5 g / m 2.
^{If two} or more platings are performed, the desired quality can be obtained.

It is preferable to add an appropriate amount of a plating aid such as KCl or NH ₄ Cl.

(2) Chromate treatment In the present invention, the chromate treatment is performed by a usual coating type. The chromate treatment may be performed using chromate anhydride, chromate and dichromate (preferably Cr ³⁺ / total Cr <0.
An aqueous solution to which 5) is added as a main component and added with sulfate ion, phosphate ion, nitrate ion, chloride ion, fluorine ion or fluorine compound or silicate colloid is applied by a spray or a roll coater, and the Zn alloy plating is performed. Forms a hydrated chromium oxide.

The adhesion amount of the chromate film is 0.1 in Cr conversion.
It is limited to 5~120mg / m ^2. The reason is 0.5
poor in the secondary adhesion after humidity test is less than mg / m ^2, C contained in the coating during exceeds 120 mg / m ²
This is because r ⁶⁺ increases and the quality of the resin is deteriorated when the organic resin is bonded and applied.

If washing after the chromate treatment is necessary, washing with water may be sufficient, but washing with hot water is more effective for sufficient washing.

The reason for limiting the high temperature drying conditions of the chromate to 120 ° C. or higher as the ambient temperature is as follows. If the temperature is lower than 120 ° C., it is difficult to reach the temperature of the dried plate, and the productivity is increased. Further, the drying plate temperature is set to be in the range of 100 to 300 ° C. When the drying plate temperature is lower than 100 ° C., H ₂ O remaining in the chromate film corrodes the plating layer at the time of resin bonding / application or generates bubbles. This may cause poor adhesion. When the temperature exceeds 300 ° C., alloying of the plating starts, and the plating becomes brittle and the adhesiveness is reduced.

(3) Organic Resin Treatment Further, a water-soluble, water-dispersible, solvent-based organic resin is applied on the chromate film. Examples of the resin in this case include polymer compounds such as alkyd resins, amino alkyd resins, acrylic resins, epoxy ester resins, and urethane resin acid-modified polyester resins. A sol such as silicon, titanium, or aluminum may be added to the polymer compound for the purpose of improving corrosion resistance.

The resin adhesion amount is limited to 0.2 to 2.0 g / m ² . The reason is that if the resin content is less than 0.2 g / m ² , the corrosion resistance after bonding is inferior. On the other hand, if it exceeds 2.0 g / m ² , it becomes difficult to release gas during bonding. In addition,
These may be applied by a generally used method.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments.

(Embodiment 1) Under the conditions shown in Table 1, an electro-zinc alloy plating and a coating type chromate treatment were performed, and a resin film was formed on a part thereof, and an adhesion test was performed on these by the following method. evaluated. In addition, it carried out similarly about the steel plate which does not form a resin film.

(Test Method 1) A test piece was obtained by bonding a PVC sheet to a surface-treated steel sheet obtained as shown in Table 1 using a polyester-based adhesive. A 2 mm square cut was cut into the base steel sheet with a cutter, and the cellophane tape was peeled off, and the following four grades were evaluated according to the degree of peeling. Forced peeling of cellophane tape 30 hours after 120 hours wet (60 ° C, 95% humidity or more)
Peeling test in minutes

(Test Method 2) An epoxy resin sheet (100 μm) for a printed circuit board was adhered to the surface-treated steel sheet obtained as shown in Table 1 at 180 ° C. for 20 minutes to obtain a test piece. A 2 mm square cut was cut into the base steel sheet with a cutter, and the cellophane tape was peeled off, and the following four grades were evaluated according to the degree of peeling. Peeling test within 30 minutes after standing for 24 hours in a vapor pressure of 134 ° C. and 3 atm. After 120 hours of wetting (60 ° C. 90% or more) 26
Peeling test after immersion in a solder bath at 0 ° C. for 1 minute ◎ —No peeling at all. −- small peeling. Δ-large peeling. X-already peeled before cutting.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3]

[0034]

According to the method of the present invention, the surface treatment with excellent adhesiveness can be achieved by controlling the trace components in the zinc alloy plating solution, selecting a condition after the coating type chromate treatment, and performing high temperature drying. A steel sheet is obtained.

──────────────────────────────────────────────────の Continuing on the front page (72) Nobuo Totsuka, Inventor No. 1, Kawasaki-cho, Chiba-shi, Chiba Kawasaki Steel Corporation Research and Development Headquarters (56) References JP-A-3-24294 (JP, A) JP-A-2-54779 (JP, A) JP-A-61-183491 (JP, A) JP-A-63-109190 (JP, A) JP-A-59-31889 (JP, A) (58) Int.Cl. ⁶ , DB name) C25D 1/00-7/12 B32B 15/08

Claims (2)

(57) [Claims] 1. A steel sheet or a galvanized steel sheet surface,
Ni ²⁺ and / or Co ²⁺ in a total of 0.05 to 5 g /
and electroplating with an electric zinc alloy at a current density of 20 to 200 A / dm ² in an acidic zinc plating bath having a pH of 1 to 6 in which Total Fe as an impurity is limited to 2 g / l or less and Pb to 2 mg / l or less. Next, 0.5 in terms of Cr
After forming a coating type chromate film of up to 120 mg / m ² , the ultimate plate temperature is 100 to 30 at an ambient temperature of 120 ° C. or more.
A method for producing a surface-treated steel sheet having excellent adhesion, characterized by drying at a temperature of 0 ° C. 2. A water-soluble, water-dispersible or organic solvent-based organic high molecular compound as an organic resin film on a surface-treated steel sheet obtained by the method according to claim 1 in a dry weight of 0.2 to 2%. A method for producing a surface-treated steel sheet having excellent adhesiveness, wherein the surface-treated steel sheet has an adhesion of 0.0 g / m ² .