JPH09296276A - Zinc-based galvanized steel sheet for organic resin coated steel sheet with excellent processing adhesion - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a zinc-based plated steel sheet for an organic resin-coated steel sheet, which is excellent in work adhesion when it is processed at high speed such as press forming. A zinc-based plated steel sheet for an organic resin-coated steel sheet, comprising a zinc-based plated layer and a chemical conversion treatment layer on a steel sheet, and coating an organic resin film having a film thickness of 100 μm or more via an adhesive layer. The treated layer has an average silica particle size of 4
It is a film formed by applying a treatment liquid containing a wet type colloidal silica of ˜200 nm and drying it, and the silica adhesion amount Y (mg / m ² ) is SiO ₂
In conversion, 10 + 0.92X + 0.015X ² ≦ Y ≦ 52 + 5.6
It is in the range of 5X-0.004X ² (where X is the average particle diameter of silica expressed in nm).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zinc-based plated steel sheet for an organic resin-coated steel sheet having excellent work adhesion.

[0002]

2. Description of the Related Art In recent years, a surface-treated steel plate called a laminated steel plate (a zinc-based plated steel plate to which a sheet-shaped resin is attached with an adhesive) has been widely used for home appliances and building materials. When high corrosion resistance is required for these steel sheets, zinc-based plated steel sheets are used, and further phosphate treatment or chromate treatment is performed as a pretreatment for the base. However, these steel sheets do not always have sufficient performance as shown below.

Phosphate treatment produces phosphate crystals on the surface of the steel sheet. However, since these crystals have poor toughness and are weak in deformation, even if a laminated steel sheet having excellent ductility is used, when they are subjected to a high degree of forming processing. Peeling occurs.

On the other hand, since the chromate-treated film is an amorphous film and has a small amount of adhesion, it is considered to be advantageous for the adhesiveness during molding, and various improvements have been made so far. For example, as a technique for improving processing adhesion, a chromate treatment method to which dry type colloidal silica is added is known as disclosed in Japanese Patent Publication No. 61-1508. However, since dry silica easily aggregates in water and changes the viscosity of the treatment liquid, it is difficult to form a uniform film, and as a result, it is difficult to obtain stable characteristics.

Further, as an example of using a wet type silica, a method of containing colloidal silica having a particle diameter of 40 to 100 nm disclosed in JP-A-63-307281 in a chromate film to improve working adhesion. Alternatively, a method using a linear silica sol has been proposed as disclosed in JP-A-4-9478. However, although these wet silicas are easily dispersed in water to form a uniform film, there is a problem that the effect of improving the adhesion is poorer than that of dry silica.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances and has a film thickness of 1 through an adhesive layer.
An object of the present invention is to provide a zinc-based plated steel sheet for an organic resin-coated steel sheet, which is used for an organic resin-coated steel sheet forming an organic resin film having a thickness of 00 μm or more and has excellent process adhesion when processed at high speed such as press forming. .

[0007]

In order to solve the above-mentioned problems, the present invention has an organic resin film having a zinc-based plating layer and a chemical conversion treatment layer on a steel sheet and having a film thickness of 100 μm or more via an adhesive layer. A zinc-based plated steel sheet for an organic resin-coated steel sheet for coating, wherein the chemical conversion treatment layer is applied with a treatment liquid containing wet type colloidal silica having an average particle diameter of individual silica particles of 4 to 200 nm, and dried. Is a film formed by applying S, and the silica adhesion amount Y (mg / m ² ) is S
In iO ₂ ^{terms, 10 + 0.92X + 0.015X 2 ≦} Y ≦ 52 + 5.6
Provided is a zinc-based plated steel sheet for an organic resin-coated steel sheet having excellent work adhesion, which is in the range of 5X-0.004X ² (where X is the average particle size of silica expressed in nm).

Further, the treatment liquid contains chromic acid or a mixture of chromic acid and a chromic acid reduction product, and the coating film is formed by applying the treatment liquid and then drying it.
The adhering amount of r may be 1 to 50 mg / m ² .

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION By adhering wet type colloidal silica having a specific average particle size to the surface of a steel sheet, the present inventors can significantly improve the adhesion when processed at high speed. They have found what they can do, and have completed the present invention.

Hereinafter, the present invention will be described specifically.

The present invention is premised on a zinc-based plated steel sheet for organic resin-coated steel sheet having a zinc-based plated layer, a chemical conversion treatment layer, an adhesive layer and an organic resin film having a film thickness of 100 μm or more on the steel sheet. Is a film formed by applying a treatment liquid containing a wet type colloidal silica having an average particle diameter of individual silica particles of 4 to 200 nm and drying the same, and its silica adhesion amount Y (mg / m ² ). Is SiO
_In terms of ₂ , 10 + 0.92X + 0.015X ² ≦ Y ≦ 52 + 5.6
It is characterized in that it is in the range of 5X-0.004X ² (where X is the average particle diameter of silica expressed in nm).

The present inventors have studied the adhesion effect of wet silica as a laminate base, and as a result, when the average particle diameter of silica is X (nm), the adhesion amount is calculated by 10+.
It found that 0.92X + 0.015X excellent adhesion force ² at determined value or more is obtained. If the amount of adhesion is less than this value, the effect is poor, and the adhesiveness during high-speed bending is particularly poor.

Further, the adhered amount is calculated by the formula 52 + 5.65X-
If the value exceeds 0.004 × ² , silica tends to coagulate and break in the film during processing deformation, resulting in poor processing adhesion.

The average particle size of the colloidal silica used at this time is preferably in the range of 4 to 200 nm. The average particle size of 4 nm or more means that it is physically very difficult to prepare silica having a particle size of less than 4 nm.
This is because the film becomes a very brittle film and the processing adhesion deteriorates. Further, the reason why the average particle diameter is set to 200 nm or less is that if the average particle diameter exceeds 200 nm, the cohesive force between silica particles is poor and the film-forming property is poor, so the effect is poor. It should be noted that only the average particle diameter of the colloidal silica in the treatment liquid is specified in the present invention, and therefore silica having several kinds of particle diameters may be mixed.

As described above, in the present invention, the average particle size is 4 to 4.
When wet type colloidal silica of 200 nm is used and the average particle diameter of silica is X (nm), the silica adhesion amount Y (mg / m ² ) is 10 + 0.92X + 0.015X ² ≦ Y ≦ in terms of SiO _2. 52 + 5.6
It is necessary to form a chemical conversion treatment layer composed of a film in the range of 5X-0.004X ² .

Chromic acid or a mixture of chromic acid and a chromic acid reduction product may be contained in the treatment liquid for forming the chemical conversion treatment layer. By including Cr in the film, it is possible to impart a primary rust preventive effect during the storage period from the film formation until the organic resin coating.
The chromium reduction rate is preferably as high as possible within the range where the treatment liquid does not gel, but is not particularly limited. Further, the amount of Cr deposited in the coating is preferably in the range of 1 to 50 mg / m ² . If it is less than 1 mg / m ² , the above-mentioned primary rust preventive effect is insufficient, and if it exceeds 50 mg / m ² , the film contains a large amount of soluble Cr ⁶⁺ , which causes a problem when dew condensation occurs.

In addition to the above, the addition of an anion component (phosphoric acid, boric acid, etc.) generally added to the chromate treatment can be applied. However, excessive addition may adversely affect the water resistant adhesion. In addition, in the present invention, application of other additives is not particularly limited.

The zinc-based plated steel sheet targeted by the present invention is
It may be a hot dip galvanized steel sheet, an electrogalvanized steel sheet, or a zinc alloy plated steel sheet. That is, the excellent work adhesion provided by the present invention is not due to the steel sheet itself, but is due to the effect of the chemical conversion treatment film formed thereon.

Next, a method for producing the galvanized steel sheet for an organic resin-coated steel sheet of the present invention as described above will be described.

In the present invention, a zinc-based plating layer is formed on a steel sheet, and any one of a hot-dip galvanized steel sheet, an electrogalvanized steel sheet and a zinc-based alloy-plated steel sheet is formed, and then the treatment liquid is applied on the plating layer. Apply and dry to form a film,
The chemical conversion layer.

As a method of applying the treatment liquid, a method capable of continuous and uniform adhesion is applied. As such a method, spray coating, dip-roll squeezing, dip-gas squeezing, roll coating, or the like can be applied. Various methods can be adopted for drying the film, and for example, it can be dried at a temperature of 60 to 150 ° C. using a hot air dryer.

Prior to applying the treatment liquid, as a pretreatment, the surface of the zinc-plated steel sheet is subjected to alkali cleaning, surface polishing, and F
Flash treatment with e, Ni, Co, Cr or the like can also be applied. Thereby, the processing adhesion can be improved. The flash treatment may be performed by bringing the treatment liquid into contact with the galvanized steel sheet by a dipping or spraying method. However, such pretreatment is not essential.

On the galvanized steel sheet of the present invention on which the chemical conversion treatment layer is formed in this manner, an organic resin film having a film thickness of 100 μm or more is formed by an ordinary adhesive layer to obtain an organic resin-coated steel sheet.

[0024]

Embodiments of the present invention will be described below.

(First Example) Wet type colloidal silica having an average particle size in the range shown in Table 1 was added to water to prepare a treatment liquid. After that, a film to be a chemical conversion treatment layer was formed on the zinc-based plated steel sheet according to the procedure described below to obtain a zinc-based plated steel sheet for an organic resin-coated steel sheet, which was subjected to laminating treatment, and Invention Example No. within the scope of the present invention. 1 to 22, Comparative Example No. 1 to
8 samples were prepared.

(1) Film forming procedure Hot-dip galvanized steel sheet (manufactured by Zenzimer line, amount of zinc deposited: 120 mg / m ² ) → washing with water → application of treatment liquid (roll coating) → drying with hot air (80 to 150 ° C.) The amount of coating film was measured by measuring the amount of SiO ₂ with fluorescent X-rays and displayed in mg / m ² .

(2) Laminating Procedure A vinyl chloride sheet was laminated on the surface-treated steel sheet obtained as described above in the following manner.

Application of urethane adhesive (film thickness: 3 μm) →
Heat treatment (plate temperature: 210 ° C) → vinyl chloride sheet (20
0 μm) Pressure bonding → water cooling → hot air drying (80 ° C.) Regarding the adhesion of each sample thus prepared,
Evaluation was performed by the following method.

(Adhesion Evaluation 1) The laminate film surface of the sample was cross-cut, and the central portion thereof was slowly extruded by an Erichsen tester by 6 mm. Then, the following four stages of classification were performed according to the film peeling condition in the central portion of the cross cut.

◎: No peeling (peeling width: 0 to less than 2 mm) ○: Slight peeling (peeling width: less than 2 to 5 mm) Δ: Partial peeling (peeling width: less than 5 to 10 mm) ×: Most peeling ( (Peeling width: 10 mm or more) (Adhesion evaluation 2) 5 kg, a spherical weight of 20φ,
The sample was placed between a pedestal having a dent (depth 6 mm) that matches the roundness, a weight was dropped from a height of 1 m, and then the adhesion evaluation 1 was made based on the peeling condition of the trace part given to the sample surface. Evaluation was performed in the same manner as in.

The processed original plate used in this example is as follows.

GI: hot-dip galvanized steel sheet; coating amount 120 g / m ² per side, zero spa material GA: alloyed hot-dip galvanized steel sheet; coating amount 45 g / m ² per surface, zero spa material EG: electrogalvanized steel sheet; Plating coverage 2 per side
0 g / m ² Al-Zn: 5% Al-Zn alloy plated steel sheet; coating amount 60 g / m ² per side The evaluation results are also shown in Table 1.

[0033]

[Table 1]

As is clear from Table 1, the samples of the invention examples according to the present invention have excellent adhesion.
On the other hand, the sample of the comparative example has insufficient adhesion, and in particular, the characteristics are inferior in bending deformation at high speed as in the adhesion evaluation 2.

(Second embodiment) Chromic anhydride 100 g / l
Methanol was added as a reducing agent to the aqueous solution of. After the addition, stirring was performed for 2 hours at a liquid temperature of 90 to 95 ° C. to reduce a part of chromium. Next, colloidal silica (particle size 4 to 20) was added to the mixed solution of chromic acid and a chromic acid reduction product.
0 nm) was added to prepare a chromate-treated solution. Table 2
Shows the composition of the treatment liquid in this case.

Then, using the prepared chromate treatment solution, the zinc-based plated steel sheet was subjected to chromate treatment and lamination treatment in the same procedure as in the first embodiment, and the invention example No.
23 to 39, Comparative Example No. 9 to 14 samples were prepared. The coating amount was measured by measuring the total amount of Cr and the amount of SiO ₂ with fluorescent X-rays and displayed in mg / m ² .

The adhesion of the samples thus prepared was evaluated in the same manner as in the first embodiment. The results are also shown in Table 2.

[0038]

[Table 2]

As is clear from Table 2, the samples of the invention examples according to the present invention have excellent adhesion, whereas the samples of the comparative examples have insufficient adhesion, and in particular, the adhesion evaluation 2 It was confirmed that the characteristics were inferior in bending deformation at such high speed.

[0040]

As described above, according to the present invention,
When forming an organic resin-coated steel sheet for forming an organic resin film having a film thickness of 100 μm or more through an adhesive layer, the adhesion to an organic resin film such as a coating or a laminate film, which has been insufficient in the past, is improved. Therefore, it is possible to obtain a zinc-based plated steel sheet for an organic resin-coated steel sheet having a high level of work adhesion such as bending at high speed. Therefore, it can be applied to applications in which such a high level of processing adhesion is required. Moreover, since the treatment method is simple, the industrial value of the present invention is extremely high.

[Brief description of drawings]

FIG. 1 is a diagram showing the scope of the present invention.

Claims (2)

[Claims] 1. A zinc-based plated steel sheet for an organic resin-coated steel sheet, comprising a zinc-based plated layer and a chemical conversion treatment layer on a steel sheet, and coating an organic resin film having a film thickness of 100 μm or more through an adhesive layer, The chemical conversion treatment layer is a film formed by applying a treatment liquid containing a wet type colloidal silica having an average particle diameter of individual silica particles of 4 to 200 nm and drying, and the silica adhesion amount Y ( mg / m ² ) is S
In iO ₂ ^{terms, 10 + 0.92X + 0.015X 2 ≦} Y ≦ 52 + 5.6
A zinc-based plated steel sheet for an organic resin-coated steel sheet having excellent work adhesion, which is in the range of 5X-0.004X ² (where X is the average particle diameter of silica expressed in nm). 2. The treatment liquid contains chromic acid, or a mixture of chromic acid and a chromic acid reduction product, and the coating film is dried after coating the treatment liquid so that the amount of deposited Cr is 1 or less. The zinc-based plated steel sheet for an organic resin-coated steel sheet having excellent work adhesion according to claim 1, wherein the galvanized steel sheet has a workability of up to 50 mg / m ² .