KR100671913B1 - Compositions for Surface Treatment of Zinc-Plated Steel Plate - Google Patents

Abstract

The present invention provides a surface treatment composition for galvanized steel sheet characterized in that 0.2 to 50 parts by weight of (A) hydrazine derivative and 0.1 to 30 parts by weight of acid capable of etching zinc (B) are dispersed or dissolved in 1,000 parts by weight of water. And the surface treatment composition on the surface of the zinc-based plated steel sheet so as to have a hydrazine derivative of 20 to 100 mg / m 2, and to dry the surface-treated method of the zinc-based plated steel sheet.

According to this invention, the surface treatment composition which can provide the zinc-based plated steel plate excellent corrosion resistance more than chromium salt treatment or phosphate treatment, and can obtain the surface-treated galvanized steel plate with favorable paint adhesiveness is obtained.

Galvanized steel sheet, hydrazine derivative, surface treatment composition, corrosion resistance, adhesion

Description

Compositions for Surface Treatment of Zinc-Plated Steel Plates

The present invention relates to a surface treatment composition for zinc-based galvanized steel sheet excellent in paint adhesion and corrosion resistance, a surface treatment method using the composition, and a surface-treated galvanized steel sheet.

In recent years, the corrosion resistant coated steel sheet is required to have excellent corrosion resistance, and a surface-treated steel sheet using a galvanized steel sheet as a substrate is often used in place of a conventional cold rolled steel sheet.

Conventionally, chromate salt treatment and zinc phosphate treatment have been generally performed as a surface treatment of a galvanized steel sheet, but toxicity of chromium has been a problem. Chromate treatment has problems such as volatilization of chromium toxic gas in the treatment process, a considerable cost for the wastewater treatment facility, and a problem due to elution of chromic acid from the chemical conversion coating. In addition, hexavalent chromium compounds are extremely harmful because many public bodies, including the IARC (International Agency for Research on Cancer Review), have been designated as carcinogenic to humans.

In addition, since zinc phosphate treatment is usually rinsed with chromic acid after zinc phosphate treatment, there is a problem of chromium treatment, and the reaction promoter, drainage treatment of metal ions and the like in the zinc phosphate treatment agent, and the treatment of metal ions from the metal to be treated. There is a problem of sludge treatment by elution.

As a treatment method other than the chromium salt treatment and the zinc phosphate treatment, (1) a surface treatment method which is treated with an aqueous solution containing aluminum phosphate and then heated to a temperature of 150 to 550 ° C. (Japanese Patent Publication No. 78-28857) Reference), (2) a method of treatment with an aqueous solution containing tannic acid (see Japanese Patent Application Laid-Open No. 76-71233), and the like, and (3) sodium nitrite, sodium borate, imidazole, and aromatic carboxylic acid , A treatment method using a surfactant, or the like, or a combination thereof.

However, the method of (1) does not have sufficient adhesiveness when the paint is applied thereon, the method of (2) is poor in corrosion resistance, and the methods of (3) are all exposed to a high temperature and high humidity atmosphere. There is a problem that corrosion resistance is poor.

It is an object of the present invention to eliminate toxic problems with chromium compounds, such as chromium salt treatment or zinc phosphate treatment, or drainage treatment of metal ions or the like, sludge treatment by elution of metal ions from the metal to be treated, and the like. It is providing the surface treatment composition which can obtain the surface-treated galvanized steel plate which can exhibit coating adhesiveness and corrosion resistance more than the grade equivalent to the case of zinc phosphate treatment.

The present inventors have found that the above object can be achieved by an aqueous surface treatment composition containing a specific corrosion resistance improver and an acid that becomes an etchant and has completed the present invention.

That is, the present invention is characterized in that the surface of the zinc-based galvanized steel sheet is formed by dispersing or dissolving 0.2 to 50 parts by weight of (A) hydrazine derivative and 0.1 to 30 parts by weight of acid capable of etching (B) zinc in 1,000 parts by weight of water. To provide a treatment composition.

The present invention also provides a surface treatment method for a galvanized steel sheet, wherein the surface treatment composition is coated and dried such that the hydrazine derivative is 20 to 100 mg / m 2.

Moreover, this invention provides the galvanized steel plate surface-treated with the said surface treatment composition.

First, the surface treatment composition of this invention is demonstrated.

The composition of the present invention is a surface treatment composition obtained by dispersing or dissolving an acid capable of etching (A) hydrazine derivative and (B) zinc in water.

(A) hydrazine derivative

Specific examples of the (A) hydrazine derivative include, for example, carbohydrazide, propionic acid hydrazide, salicylic acid hydrazide, adipic acid hydrazide, sebacic acid hydrazide, dodecanediohydrazide, isophthalic acid dihydrazide, thio Hydrazide compounds such as carbohydrazide, 4,4'-oxybisbenzenesulfonylhydrazide, benzophenonehydrazone and aminopolyacrylamide; Pyrazole compounds such as pyrazole, 3,5-dimethylpyrazole, 3-methyl-5-pyrazolone and 3-amino-5-methylpyrazole; 1,2,4-triazole, 3-amino-1,2,4-triazole, 4-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 5 -Amino-3-mercapto-1,2,4-triazole, 2,3-dihydro-3-oxo-1,2,4-triazole, 1H-benzotriazole, 1-hydroxybenzotriazole (Monohydrate), 6-methyl-8-hydroxytriazolopyridazine, 6-phenyl-8-hydroxytriazolopyridazine, 5-hydroxy-7-methyl-1,3,8-triazaindolidine Triazole compounds such as these; Tetrazole compounds such as 5-phenyl-1,2,3,4-tetrazole and 5-mercapto-1-phenyl-1,2,3,4-tetrazole; Thiazole compounds such as 5-amino-2-mercapto-1,3,4-thiadiazole and 2,5-dimercapto-1,3,4-thiazole; Maleic acid hydrazide, 3,6-dichloropyridazine, 6-methyl-3-pyridazone, 4,5-dichloro-3-pyridazone, 4,5-dibromo-3-pyridazone, 6-methyl-4 Pyridazone compounds, such as a 5-5-hydrohydropyridazone, etc. are mentioned. Especially, the pyrazole compound and triazole compound which have a 5- or 6-membered cyclic structure and has a nitrogen atom in a cyclic structure are suitable. These hydrazine derivatives can be used individually by 1 type or in mixture of 2 or more types.

(B) acids capable of etching zinc

(B) The acid capable of etching zinc may be any acid which is stable in the composition of the present invention and capable of etching zinc. For example, hydrofluoric acid, hydrobromic acid, hydroiodic acid, boric fluoride acid, titanium fluoride, silicic acid Inorganic acids such as hydrofluoric acid, sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid; Organic acids such as acetic acid, chloroacetic acid, trichloroacetic acid, lactic acid and tartaric acid. These can be used 1 type or in mixture of 2 or more types. Among these, phosphoric acid can be used preferably.                     

(B) An acid capable of etching zinc dissolves zinc on the surface of the coating when the composition of the present invention is applied to a zinc-based plated steel sheet, and zinc ions generated by this dissolution are coated with (A) hydrazine derivative. It is thought that a firm film excellent in corrosion resistance can be formed.

In the surface treatment composition of the present invention, the compounding amount of each component is in the range of 0.2 to 50 parts by weight, preferably 1 to 10 parts by weight of (A) hydrazine derivative, based on 1,000 parts by weight of water, and (B) zinc is etched. Suitable acids are in the range of 0.1 to 30 parts by weight, preferably 1 to 5 parts by weight.

The composition of the present invention contains, as an essential component, an acid capable of etching the (A) hydrazine derivative and (B) zinc in water, and may further contain an organic solvent, a neutralizing agent, an oxidizing agent, etc. as appropriate.

As said organic solvent, if it is a solvent which can melt | dissolve or disperse the said component (A) and (B), it can use without a restriction | limiting in particular.

The said neutralizing agent is mix | blended as needed in order to neutralize and form an aqueous film forming organic resin, and when said resin is a cationic resin, acids, such as an acetic acid, lactic acid, formic acid, can be used as a neutralizing agent.

The oxidant (B) has a function of assisting the action of an acid capable of etching zinc, and examples thereof include hydrogen peroxide, perborate salt, permanganate salt, nitrite salt, nitrate salt, chlorate salt and bromate salt. Can be. Especially, hydrogen peroxide can be used preferably.                     

Next, the surface treatment method of the zinc-based galvanized steel plate of this invention using the surface treatment composition of this invention is demonstrated.

The surface treatment method of the present invention is characterized by coating and drying the surface treatment composition of the present invention on the surface of a galvanized steel sheet.

Examples of the galvanized steel sheet to be surface treated include hot dip galvanized steel sheets, electrogalvanized steel sheets, iron-zinc alloy plated steel sheets, nickel-zinc alloy plated steel sheets, and aluminum-zinc alloy plated steel sheets (for example, "garbarium" and "gar Plate "), and the like. As the zinc-based plated steel sheet, a zinc-based plated steel sheet subjected to chemical conversion treatment such as chromium salt treatment, zinc phosphate treatment, and composite oxide film treatment can also be used.

Although the coating amount of the surface treatment composition of this invention on a galvanized steel plate is not specifically limited, Usually, the amount of the hydrazine derivative is in the range which is 20-100 mg / m <2>, Preferably it is 30-80 mg / m <2>. It is suitable from a viewpoint of corrosion resistance, workability, etc.

In applying the surface treatment composition of the present invention onto a galvanized steel sheet, the composition of the present invention is usually adjusted to a viscosity with water in the range of, for example, about 5 to 100 mPa · s according to the coating amount, and roll coater coating, Surface treatment can be performed by apply | coating by a coating method, such as spray coating, brush painting, and squeeze coating which squeezes and removes the liquid remaining after liquid application, and heats and dries. Drying conditions are not particularly limited as long as the coated surface treatment composition can be dried. However, when the coated object is continuously dried in a sheet form, it is usually about 10 to 100 seconds at an ambient temperature of 100 to 250 ° C (steel sheet It is preferable to heat the highest achieved temperature of 80-150 degreeC).

The surface-treated galvanized steel sheet obtained by the surface treatment method of the present invention may be used as a rust-prevented steel sheet as it is excellent in corrosion resistance, workability, etc., but also has excellent coating film adhesion, and is thus coated on the surface-treated zinc-based galvanized steel sheet again. May be formed. What is necessary is just to select suitably the composition which forms this upper layer film according to the objective, and various coating compositions can be used. As this coating composition, a lubricating film forming composition, a high corrosion resistant film forming composition, a primer coating, a colored top coat etc. are mentioned, for example. A lubricating film forming composition, a high corrosion resistant film forming composition, or a primer paint can be coated and dried, and a colored top coat can be coated thereon again.

Hereinafter, an Example and a comparative example demonstrate this invention further more concretely. In the following, "part" and "%" mean "weight part" and "weight%", respectively.

<Example 1>

Water was added to an aqueous hydrofluoric acid solution having a concentration of 36% to obtain an aqueous hydrofluoric acid solution having a concentration of 3%. In addition, 10 g of 3,5-dimethylpyrazole and 90 g of water were separately blended into a mayonnaise bottle, glass beads were added and dispersed in a paint mixer to obtain a dispersion having a solid content of 10%. 100 parts of this dispersion, 333.3 parts of hydrofluoric acid solution and 586.7 parts of water were mixed with 3% of a flu to obtain a surface treatment composition.

<Examples 2 to 17 and Comparative Examples 1 to 2>                     

As a kind of acid which can be etched zinc, the aqueous solution of the acid of 3% concentration was obtained using what is shown in following Table 1, and it is disperse | distributed in water using the thing shown in following Table 1 as a kind of hydrazine derivative, and dispersion of solid content of 10% Each surface treatment composition was obtained like Example 1 except having obtained these and mixing these and water so that the quantity of each component with respect to 1,000 parts of water may become the compound of Table 1 below.

Acids That Can Etch Zinc Hydrazine derivatives Kinds Quantity (part) Kinds Quantity (part) Example 1 Hydrofluoric acid 10  3,5-dimethylpyrazole 10 Example 2 Hydrofluoric acid 10  3-amino-1,2,4-triazole 10 Example 3 Hydrofluoric acid 10  3-mercapto-1,2,4-triazole 10 Example 4 Hydrofluoric acid 30  3,5-dimethylpyrazole 10 Example 5 Hydrofluoric acid 10  3-amino-1,2,4-triazole 30 Example 6 Hydrofluoric acid 10  3-mercapto-1,2,4-triazole 50 Example 7 Sulfuric acid 10  3,5-dimethylpyrazole 10 Example 8 Formic acid 10  3-amino-1,2,4-triazole 50 Example 9 Acetic acid 10  3-mercapto-1,2,4-triazole 30 Example 10 Lactic acid 30  3,5-dimethylpyrazole 20 Example 11 Phosphoric Acid 10  3,5-dimethylpyrazole 20 Example 12 Phosphoric Acid 10  3-amino-1,2,4-triazole 20 Example 13 Phosphoric Acid 10  3-mercapto-1,2,4-triazole 20 Example 14 Phosphoric Acid 30  3,5-dimethylpyrazole 20 Example 15 Phosphoric Acid 10  3-amino-1,2,4-triazole 30 Example 16 Phosphoric Acid 10  3-amino-1,2,4-triazole 30 Example 17 Phosphoric Acid 30  3,5-dimethylpyrazole 10 Comparative Example 1 - -  3-mercapto-1,2,4-triazole 10 Comparative Example 2 Hydrofluoric acid 10 - -

In Table 1, the amounts of each component were expressed as the amount of the active ingredient for the acid capable of etching zinc and the amount of solids for the hydrazine derivative.

<Production of Test Plate>

Each test plate was manufactured by the following coating method (1) and coating method (2) using each surface treatment composition obtained in the said Examples 1-17 and Comparative Examples 1-2.

<How to paint (1)>                     

<Examples 18 to 34 and Comparative Examples 3 to 4>

After degreasing and washing an electrogalvanized steel sheet having a plate thickness of 0.6 mm and a plating adhesion amount of 20 g / m 2 on one side, the amount of hydrazine derivative obtained in each of the surface treatment compositions obtained in Examples 1 to 17 and Comparative Examples 1 and 2 was placed thereon. It coated with the spinner so that it might be set to mg / m <2>, and it baked for 15 second on condition that PMT (the highest achieved temperature of a steel plate) will be 100 degreeC, and obtained each process board. Subsequently, Cosmer 2050 (Kansai Paint Co., Ltd. product, brand name, acrylic / silica composite resin liquid) was coated on each of the obtained treated plates so as to have a dry film thickness of 3 μm, and baked for 20 seconds under the condition that PMT was 120 ° C. Each test plate was prepared.

Comparative Example 5

After degreasing and cleaning an electrogalvanized steel sheet having a plate thickness of 0.6 mm and a plating adhesion amount of 20 g / m 2 on one side, the uncoated surface treatment composition was used, and the cosmer 2050 was coated thereon to have a dry film thickness of 3 μm. , PMT was baked for 20 seconds under the condition of 120 ° C to obtain a test plate.

The corrosion resistance test was done about each test plate. The test results are shown in Table 2 below. The test was carried out according to the following test method.

Corrosion resistance: A salt spray test specified in JIS Z2371 is carried out to the test plate which seals the cross section and the back of the test plate for up to 240 hours, and the degree of rust of the coating film surface after 120 hours and after 240 hours has been determined. Evaluated.

a: The occurrence of white rust was not confirmed,                     

b: the occurrence of white blue is less than 5% of the coating film area;

c: the occurrence of white blue is more than 5% of the coating film area and less than 10%,

d: the occurrence of white blue is more than 10% of the coating film area and less than 50%,

e: The generation | occurrence | production degree of white blue is 50% or more of a coating-film area.

How to paint (1) Surface treatment compositions Corrosion resistance Type (example number) 120 hours 240 hours Example 18 Example 1 a a Example 19 Example 2 a b Example 20 Example 3 a a Example 21 Example 4 a a Example 22 Example 5 a a Example 23 Example 6 a a Example 24 Example 7 a a Example 25 Example 8 a a Example 26 Example 9 a b Example 27 Example 10 a b Example 28 Example 11 a a Example 29 Example 12 a b Example 30 Example 13 a b Example 31 Example 14 a b Example 32 Example 15 a b Example 33 Example 16 a a Example 34 Example 17 a b Comparative Example 5 Comparative Example 1 c d Comparative Example 4 Comparative Example 2 d e Comparative Example 6 No surface treatment d e

<Coating method (2)>

<Examples 35 to 51 and Comparative Examples 6 to 7>

After degreasing and cleaning a hot dip galvanized steel sheet having a plate thickness of 0.4 mm and a plating adhesion amount of 120 g / m 2 on one side, the amount of hydrazine derivative obtained in each of the surface treatment compositions obtained in Examples 1 to 17 and Comparative Examples 1 and 2 was placed thereon. It coated with the spinner so that it might become g / m <2>, and baked for 15 second on the conditions which PMT becomes 100 degreeC, and obtained the process board. Subsequently, a KP Color 8000 primer (manufactured by Kansai Paint Co., Ltd., a modified epoxy resin primer coating material) was coated on the treated plate so as to have a dry film thickness of 5 μm, and baked for 20 seconds under the condition that the PMT is 210 ° C. to coat the primer coating film. Then, KP Color 1580 White (manufactured by Kansai Paint Co., Ltd., thermosetting polyester resin paint, white) was coated on the primer coating film so as to have a dry film thickness of 20 µm, and the PMT was 215 ° C. Each test plate with a top coat was prepared by baking for 40 seconds.

<Comparative Example 8>

After degreasing and washing the hot-dip galvanized steel sheet of plate thickness 0.4mm and the plating adhesion amount of 120g / m <2> of a single side, the thing which did not coat the surface treatment composition was used, and the primer coating film and the top coat film were carried out on it similarly to the coating method (2) To form a test plate.

The test of the adhesiveness, corrosion resistance, and moisture resistance of an upper coating film was performed about these test coating boards according to the following test methods. The test results are shown in Table 3 below.

<Test method>

Adhesion of the upper coating film: 100 1 mm scales were made by inserting 11 grooves each vertically and horizontally into a checkerboard with a knife on the coating film surface. The peeling degree of the upper coating film when the cellophane adhesive tape was stuck to this checkerboard eye part and peeled off the tape in an instant was evaluated by the following criteria.

a: Peeling of the upper coating film was not confirmed at all,

b: 1 to 2 peelings of the upper coating film were confirmed.                     

c: 3-10 peeling of the upper coating film was confirmed,

d: 10 or more peelings of the upper coating film were confirmed.

Corrosion resistance: After sealing the cross section and the back surface of the test plate having the upper coating film cut to a size of 70 × 150 mm, the 4T bent portion (0.4 mm thick spacer 4 on the top of the coating film outside) was sealed. A salt spray test specified in JIS Z2371 was conducted for 1,000 hours on a coated plate provided with a cross cut portion provided at the bottom of the test plate. In the coating plate after the test, the degree of occurrence of white blue at the 4T bent portion, the swelling width of the cross cut portion, and the degree of swelling of the general portion (processing, the center portion without cut) were evaluated based on the following criteria.

[Occurrence of White Blue in 4T Bends]

a: The occurrence of white rust was not confirmed,

b: slight white rust,

c: white blue occurs considerably,

d: White rust is remarkably generated.

[Swelling width of cross cut part]

a: one side swelling width in cross cut is less than 1 mm,

b: One side swelling width in cross cut is 1 mm or more and less than 2 mm,

c: one side swelling width in a cross cut is 2 mm or more and less than 5 mm,

d: One side swelling width in cross cut is 5 mm or more.

[Inflation degree of general part]                     

a: swelling has not been confirmed,

b: slight swelling is observed,

c: significant swelling has been identified,

d: Significant swelling occurred.

Moisture resistance: The test plate which sealed the cross section and back surface part of the test plate which has an upper layer coating film was subjected to the moisture test according to JIS K5400 9.2.2. The temperature in the humidity tester box was 49 ° C, the relative humidity was 95 to 100%, and the test time was 1,000 hours. After the test, the degree of swelling of the coating film of the test plate was evaluated by the following criteria.

a: swelling has not been confirmed,

b: slight swelling is observed,

c: significant swelling has been identified,

d: Significant swelling occurred.                     

How to paint (2) Surface treatment composition type (example number) Adhesion of the upper coating Corrosion resistance 4T bend Cross cut General Department Moisture resistance Example 35 Example 1 a a a a a Example 36 Example 2 a a a a a Example 37 Example 3 a a a a a Example 38 Example 4 a a a a a Example 39 Example 5 a a a a a Example 40 Example 6 a a a a a Example 41 Example 7 a b a a a Example 42 Example 8 a b b a a Example 43 Example 9 a b b a a Example 44 Example 10 a b b a a Example 45 Example 11 a a a a a Example 46 Example 12 a b b a b Example 47 Example 13 a b b a b Example 48 Example 14 a b b a b Example 49 Example 15 a b b a b Example 50 Example 16 a a a a a Example 51 Example 17 a b b a b Comparative Example 6 Comparative Example 1 a c c c c Comparative Example 7 Comparative Example 2 a d d c c Comparative Example 8 No surface treatment a d d d c

The composition of the present invention can be subjected to a surface treatment excellent in corrosion resistance and coating film adhesion to a galvanized steel sheet, and can be used in place of a surface treatment such as conventional zinc phosphate treatment or chromate treatment. Since the composition of the present invention does not generate sludge at the time of surface treatment and does not use a chromium compound, there is no toxicity problem caused by the chromium compound, thus eliminating the problem of environmental preservation.

When the galvanized steel sheet surface-treated with the composition of the present invention has a coating film formed thereon, it can be said that the adhesion with the coating film is also excellent, so that the use of a colored galvanized steel sheet is used, for example, building materials, home appliances, automobiles. It can also be used for applications such as parts.

Claims (5)

0.2 to 50 parts by weight of (A) hydrazine derivative and 0.1 to 30 parts by weight of acid capable of etching zinc (B) are dispersed or dissolved in 1,000 parts by weight of water. The composition of claim 1, wherein the acid capable of etching (B) zinc is phosphoric acid. The composition according to claim 1 or 2, wherein the (A) hydrazine derivative is a pyrazole compound or a triazole compound. The surface treatment composition of a zinc-based galvanized steel sheet is apply | coated and dried so that the surface treatment composition of Claim 1 may be 20-100 mg / m <2>. The galvanized steel sheet surface-treated with the surface treatment composition of Claim 1.