KR101205505B1 - Coating compositions for a metal sheet and metal sheet comprising the same - Google Patents

Abstract

The present invention is at least one compound selected from phosphoric acid or silica; Organic acid; And relates to a coating composition for a metal sheet comprising a metal compound and a metal sheet comprising the same, the coating composition for a metal sheet according to the present invention does not deteriorate other physical properties such as workability and weldability, unlike conventional zinc phosphate-based inorganic lubricating coating At the same time, by improving the chemical affinity with the adhesive, it is possible to provide excellent adhesive adhesion.

Adhesive, Organic Acid, Metal Steel Sheet

Description

Coating compositions for metal sheet and metal sheet comprising same

The present invention relates to a coating composition for a metal steel sheet and a metal steel sheet comprising the same, and more particularly to a coating composition for a metal steel sheet for forming a coating layer having excellent processability and adhesion to zinc and zinc-based alloy plated steel sheet and a metal steel sheet comprising the same It is about.

Metallic Steel Sheet In particular, alloyed hot-dip galvanized steel sheet is a very important material for the modern industry. Its price is low and its corrosion resistance and weldability are excellent.

On the other hand, with the recent technological developments and increasing consumer demand for better products, the demand for metal alloy sheets having excellent corrosion resistance and weldability, especially alloyed hot-dip galvanized steel sheets, has been increasing. Due to the problem that the steel sheet has a low adhesion and surface lubricity between the metal and the plated layer, it is easy to generate cracks during press molding, and thus, in recent years, there is a demand for technology development to improve the steel sheet.

As such an example, many attempts have been made to improve moldability, that is, workability, and among them, a method of coating or modifying a lubricating material on a metal surface has become a mainstream. In this way, a method of coating inorganic surfaces such as phosphate-based inorganic lubricating materials, which have the advantages of low cost and excellent workability, has been used, but has a disadvantage of being poorly compatible with adhesives. As a method for coating a metal surface of an insoluble condensed zinc phosphate on the metal surface, in particular, alkali degreasing solution, such as alkali degreasing, zinc phosphate treatment, electrodeposition coating, primary coating, secondary coating, etc. There is a disadvantage in that it is extremely difficult to dissolve in acidic zinc phosphate treatment liquid, there is a problem in that the chemical conversion is poor, thereby reducing the coating adhesion or corrosion resistance after coating.

In addition, Japanese Patent No. 4,158,879 discloses that the film structure of the inorganic lubricating substance of the phosphate salt forms a dense film in the form of a polymer of insoluble condensed zinc phosphate as the surface layer, and the lower layer has a crystalline film structure in the form of soluble zinc phosphate. It has been explained that it has a two-layer structure, forming a film that can improve both adhesiveness and chemical conversion. However, the treatment process is doubled, and it is difficult and difficult to control the temperature and other conditions according to each treatment process. There is a problem.

In addition, in the case of orthophosphoric acid, when dehydration condensation is made, polyphosphate such as pyrophosphoric acid and tripolyphosphate polymerized on a straight chain is mainly used, and when dehydration condensation is further progressed, it is a phosphate constituting three-dimensional crosslinked and polymerized metaphosphate The binding state will have a great change. In addition, when the phosphate is treated on the steel sheet, the performance of the film is greatly changed according to the phosphate bonding state and the progress of the polymerization of the film. Will appear differently. The phosphate-type coating as described above has a problem in that workability can be secured because a small amount of orthophosphoric acid binds to a small amount of Mn, Ni, and the like, but the adhesion is significantly reduced.

The present invention has been proposed to solve the above problems, the technical problem of the present invention is to provide a coating composition for metal steel sheet which can form a coating film excellent in adhesion and workability between the metal material and the adhesive.

In addition, another technical problem to be solved by the present invention is to provide a metal steel sheet including a metal steel sheet and a coating layer containing the coating composition for metal steel sheet of the present invention on one side or both sides of the metal steel sheet.

The present invention

One or more compounds selected from phosphoric acid or silica;

Organic acid; And

Provided is a coating composition for a metal steel sheet containing a metal compound.

The present invention also provides a metal steel sheet comprising a metal steel sheet and a coating layer containing the coating composition for metal steel sheet of the present invention on one or both surfaces of the metal steel sheet.

The coating composition for metal steel sheet according to the present invention, unlike the conventional zinc phosphate-based inorganic lubricating film, by treating the surface of the metal material, specifically zinc or zinc-based galvanized steel sheet, does not inhibit the workability and weldability, and at the same time organic and inorganic By improving the chemical affinity with the adhesive by the complex formation of the composite of the material of the has the effect of remarkably improving the adhesion.

In particular, it has the effect of showing excellent adhesiveness with respect to various adhesives used for automobile bodies and showing adhesive suitability equal to or higher than that of an untreated material even in a pre-cure state.

The present invention

One or more compounds selected from phosphoric acid or silica;

Organic acid; And

Provided is a coating composition for a metal steel sheet containing a metal compound.

The present invention also provides a metal steel sheet including a metal steel sheet and a coating layer containing the coating composition for metal steel sheet of the present invention on one or both surfaces of the metal steel sheet.

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

At least one compound selected from phosphoric acid or silica in the coating composition for metal steel sheet of the present invention enhances lubricity closely related to processability, and the phosphoric acid is preferably 0.1 to 3 parts by weight based on 100 parts by weight of the coating composition for metal steel sheet, It is more preferable that it is 0.5-1.5 weight part. If the use amount of the phosphoric acid is less than 0.1 part by weight, the lubricity may not be improved, and if it exceeds 3 parts by weight, the conductivity of the coating may be drastically reduced, which may lead to a very poor weldability.

The silica may be used fumed silica, colloidal silica or a mixture thereof, preferably colloidal silica.

Moreover, it is preferable that it is 0.2-4 weight part with respect to 100 weight part of coating compositions for metal steel sheets, and, as for the said silica, it is more preferable that it is 0.5-3 weight part. When the amount of the silica used is less than 0.2 part by weight, the effect of improving adhesion and processability is insignificant, and when the content of the silica is more than 4 parts by weight, there is no effect of improving the adhesion and processability as well as contaminating the degreasing solution during the automobile manufacturing process. Can be.

The organic acid is complexed with at least one compound selected from a metal compound and phosphoric acid or silica to form a dense surface structure to improve corrosion resistance and to increase chemical affinity with the adhesive at the interface, thereby exhibiting high adhesion properties to the adhesive. The organic acid is preferably 0.1 to 6 parts by weight, more preferably 0.1 to 2 parts by weight based on 100 parts by weight of the coating composition for metal steel sheet. If the organic acid is less than 0.1 parts by weight, the adhesion cannot be improved. If the organic acid is more than 6 parts by weight, the acidity of the solution is very low, so that the surface is heavily etched upon contact with the steel sheet, thereby making it difficult to control the amount of adhesion.

Moreover, it is preferable that it is 0.2-7 weight part with respect to 100 weight part of coating compositions for metal steel sheets, and, as for the said metal compound, it is more preferable that it is 0.2-3 weight part. If the metal compound is less than 0.2 parts by weight, the adhesiveness and processability cannot be improved. If the metal compound is more than 7 parts by weight, the effect of improving the adhesiveness and workability is insignificant, which is uneconomical.

Further, the organic acid is not particularly limited as long as it can form a complex with phosphoric acid or silica, but may be an organic acid having one or more sulfonic acid groups or carboxyl groups in the structure. Such organic acid may be specifically selected from 4-hydroxybenzenesulfonic acid, citric acid or a mixture thereof.

As a specific example, the organic acid preferably contains 0.1 to 3 parts by weight of 4-hydroxybenzenesulfonic acid based on 100 parts by weight of the coating composition for metal steel sheet, and 0.1 to 3 parts by weight of citric acid.

The metal compound is preferably a compound containing at least one selected from molybdenum (Mo), manganese (Mn) or nickel (Ni). The compound is preferably selected from the group consisting of acetates, carbonates, ammonium salts or hydroxides of at least one metal selected from the group consisting of molybdenum (Mo), manganese (Mn) and nickel (Ni). Specifically, 0.1 to 2 parts by weight of manganese (II) acetate tetrahydrate, 0.1 to 2 parts by weight of basic nickel carbonate (Nickel (II) carbonate basic), and 0.2 to 3 parts by weight of ammonium molybdate are used. Most preferably.

In addition, the coating composition for metal steel sheet of the present invention may further include an etchant, such etching agent is preferably used 0.1 to 4 parts by weight, and 0.2 to 2 parts by weight based on 100 parts by weight of the coating composition for metal steel sheet. More preferably.

The etchant may be used without limitation, an etchant that can be commonly used in the zinc or zinc-based galvanized steel sheet, but preferably at least one selected from fluoro titanic acid or fluoro zirconium acid.

As described above, the coating composition for a metal sheet according to the present invention is characterized in that a small amount of Zn ²⁺ dissolved by an etching action when applied to a zinc or zinc-based plated steel sheet as a composite of an organic material and an inorganic material is deposited on the surface and is present in the coating composition. The organic and inorganic materials (Mo, Mn, Ni) and the like to form a complex structure of the organic and inorganic materials forming a complex, improving the chemical bonding ability between the adhesive, showing excellent adhesion to the adhesive, processability, corrosion resistance, And weldability.

Moreover, it is preferable to maintain pH of 1.3-3.5 of the coating composition for metal steel sheets. If the pH is less than 1.3 it is difficult to dissolve the film is insufficient chemical conversion treatment, when the pH exceeds 3.5 there is a problem that the chemical conversion properties are improved but the adhesiveness is lowered.

The present invention also relates to a metal steel sheet comprising a metal layer; and a coating layer containing the film composition for metal steel sheet of the present invention on one or both surfaces of the metal steel sheet.

Moreover, it is preferable to use zinc or zinc-based plated steel sheets such as hot-dip galvanized steel sheet, electro-galvanized steel sheet, zinc-based electroplated steel sheet and alloyed hot-dip galvanized steel sheet.

In addition, the coating method may be a coating method commonly used in the art, for example, a coating method such as dip coating, spray coating, roll coating or bar coating, the thickness of the coated coating layer is preferably 15nm to 40nm, More preferably, it is 18 nm-25 nm.

If the thickness of the coating layer is less than 15nm, the adhesive adhesion and workability is lowered, if it exceeds 40nm may be poor weldability due to low conductivity.

Hereinafter, the present invention will be described in detail by way of examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

≪ Example 1 >

As shown in Table 1, 0.8 parts by weight of phosphoric acid [Phosphoric acid (85%)]; 0.4 part by weight of Hexafluorotitanic acid (60%); 1 part by weight of p-Phenolsulfonic acid (65%); Citric acid 0.2 part by weight Manganese (II) acetate tetrahydrate 0.4 part by weight; 0.6 parts by weight of ammonium molybdate tetrahydrate; and 96.6 parts by weight of pure [H20] were mixed to prepare a coating composition for a steel sheet.

Then, the coating composition for the steel sheet was uniformly coated on an alkali degreased 0.7 mm thick alloyed hot-dip galvanized steel sheet (GA steel sheet) with [bar coater (No. 3)], followed by 5 seconds in a hot air drying furnace at 340 ^° C. atmosphere. Dry to form a coating.

<Example 2 and Comparative Example>

The same method as in Example 1, but the composition of each binder resin composition is shown in Table 1.

Example Comparative example Example 1 Example 2 Comparative Example 1 Phosphoric Acid 0.8 - - Colloidal silica - 1.8 - Hexafluorotitanic acid 0.4 0.4 - Para-phenolsulphonic acid One 0.9 - Citric acid 0.2 0.16 - Manganese Acetate Tetrahydrate 0.4 0.3 - Ammonium Molybdate Tetrahydrate 0.6 0.6 - Basic nickel carbonate - - - pure 96.6 95.84 -

The coating layer formed on the surface of the alloyed hot-dip galvanized steel sheet using the coating composition for metal sheets prepared according to Examples 1 and 2 and Comparative Example 1 was tested in the following manner to compare workability, shear strength, and weldability. The measurement results are shown in Table 2 and Table 3.

(1) processability

-Friction coefficient: Apply cleaning oil (PDBH) on the coating and sliding at 1000mm / min with pressing force 650kgf. The friction coefficient was measured by dividing the drawing load applied by the pressing force.

-Cup processing: Apply the cleaning oil (PDBH) to the 100mm diameter specimen and push the 50mm diameter punch at 100mm / min to increase the maximum drawing force and the molding limit. drawing force) was measured. At this time, BHF (blank holding force) was 1 ton when measuring the maximum load.

(2) shear strength

[Measurement of Shear Strength (kg / cm2)]

Cut the specimen into 100 mm x 25 mm and immerse the 5 mm end in rust-preventive oil (BW-90EG, BW-90BG) or cleaning oil (P-DBH), and then leave it for 1 day. After cutting 25 mm x 25 mm, the adhesive was applied to a thickness of 1 to 3 mm, and the two specimens thus prepared were overlapped, cured under the following curing conditions, and left to stand for one day, followed by a tensile tester (Zwick / Shear strength was measured at 50 mm / min using Roell Z050).

[Adhesive Types and Curing Conditions]

end. glue:

-Adhesive for hem flange [PV5308, Henkel Corporation])

-Mastic Sealer [Metallic, Bokwang]

I. Curing Condition:

-PV5308: 150 ℃, 10 min [pre cure state]

-Mastic Sealer: 160 ℃, 20 min [Standard state]

All. Oiling:

PM (cleaning oil, Sukimura Chemical), BG (rustproof oil, Bumwoo) and EG (rustproof oil, Bumwoo), PDBH (cleaning oil, Bumwoo)

(3) weldability

Weldability was measured by the number of continuous RBIs and the appropriate welding current range. The specimen with a thickness of .7 mm was welded at 12 cycles using a dome shape of electrode pressure of 2.3 KN and electrode tip diameter of 6 mm. The welding current was increased from 8.4kA to 11.8kA by 0.2kA, and the current when the plug fracture of the weld fracture surface began to be selected as the lower limit current, minus 0.2kA from the current when the spatter started to occur. The current was determined as the upper limit current. Continuous RBI was measured by measuring button size and nugget size at every 100 RBI by determining continuous RBI as the time when the size becomes 3.35mm or less.

Workability Evaluation Results division
Coefficient of friction
Cup Machinability Load (ton) Forming limit (ton) Comparative Example 1 0.2062 6.9 One Example 1 0.1398 5.66 4.2 Example 2 0.1387 5.85 3.3

As shown in Table 1, the coefficient of friction is very high, while Comparative Example 1 is 0.206, while Example 1 exhibits a very low value of 0.139, which is very excellent in surface slipperiness. In addition, the maximum load on the untreated material during cup processing is 6.9 tons, whereas the coating of the solution improves the surface lubrication characteristics, which means that the load is less than about 1 ton, and the maximum molding limit is more than 1 ton in Comparative Example 1. Cracking occurred, whereas in Example 1, 4.2 tons and Example 2, cracks occurred in 3.3 tons or more.

division PV5308
Mastic sealer
Remarks PM BG EG PDBH BG EG Comparative Example 1 37 35.2 24.7 10.7 10.5 6.4 Example 1 38.3 38.4 26.4 11.2 11.9 10.2 Example 2 40.6 40.4 35 10.4 10.8 10.9

Shear strength measurement result (unit: kg / cm ² )

([Glue and Oil Type]

Adhesive: PV5308 [Adhesion for Hem Flange of Japan Motor Company, Henkel Corporation]

Mastic sealer [Domestic automotive adhesive, Bokwang]

Petroleum oil: PM (Japanese car wash, Sukimura Chemical), BG (our rust preventive oil, Bumwoo) and EG (our rust preventive oil, Bumwoo), PDBH (domestic car wash, Bumwoo))

As a result of measuring the shear strength, Examples 1 and 2 satisfied 25kg / cm ² of the standard strength of PV5308 adhesive [PV5308 (Hen Flange adhesive), regardless of the type of oil, and the mastic adhesive [Mastic Sealer] (Mastic sealer), (adhesives of the domestic automobile company)] more than 8kg / cm ² of the standard showed better adhesive properties than the comparative example. In addition, Figure 1 shows a form in which the adhesive is broken after the shear strength measurement using the aforementioned tensile tester. As can be seen in Figure 1, the adhesive cohesion failure rate also showed a breakdown form equivalent to or greater than the untreated material irrespective of the type of oil and adhesive.

[Weld test results]

As a result of the weldability test of Example 1, the weldable current range was 9.2kA and the upper limit was 11.4kA, and the lower limit was 10kA and the upper limit was 11.6kA. In Example 1 and Example 2, more than 2600 strokes were found to be very good weldability.

As described above, those skilled in the art will understand that the present invention can be implemented in other specific forms without changing the technical spirit or essential features. The scope of the present invention is shown by the claims to be described later rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts are included in the scope of the present invention. Should be.

Figure 1 is a photograph showing the adhesive breakdown form for PV5308 and mastic adhesive

Claims (11)

Based on 100 parts by weight of the composition for metal surface treatment, 0.2-4 parts by weight of silica; 0.1-6 parts by weight of organic acid; And The coating composition for metal steel sheets containing 0.2-7 weight part of metal compounds. delete The method of claim 1, The organic acid film composition for a steel sheet, characterized in that it comprises at least one sulfonic acid group or carboxyl group in the structure. The method of claim 1, The organic acid is a film composition for a steel sheet, characterized in that it comprises 4-hydroxybenzenesulfuric acid, citric acid or a mixture thereof. The method of claim 1, The metal compound is a film composition for a steel sheet, characterized in that the compound containing at least one selected from the group consisting of zinc (Zn), molybdenum (Mo), manganese (Mn), nickel (Ni) and titanium (Ti). The method of claim 1, The coating composition for a metal steel sheet, the coating composition for a metal steel sheet, characterized in that it further comprises an etchant. The method according to claim 6, The coating composition for a metal steel sheet, characterized in that the etchant is at least one selected from fluoro titanic acid and fluoro zirconium acid. The method according to any one of claims 1 and 3 to 7, PH of the coating composition for metal sheets, the metal film coating composition, characterized in that to maintain 1.3 to 3.5. Metal steel sheet; and A metal steel sheet comprising a coating layer containing the coating composition for a metal steel sheet of any one of claims 1, 3 to 7 on one or both sides of the metal steel sheet. 10. The method of claim 9, The metal steel sheet is one or more zinc or zinc-based galvanized steel sheet selected from the group consisting of hot-dip galvanized steel sheet, electro-galvanized steel sheet, zinc-based electro-alloyed steel sheet and alloyed hot-dip galvanized steel sheet. 10. The method of claim 9, The thickness of the coating layer is a metal steel sheet, characterized in that 15nm to 40nm.

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