JPH07331160A - Composition, fluid, and method for treating surface of steel sheet plated with zinc-and/or aluminum-containing metal - Google Patents

Abstract

PURPOSE:To impart excellent alkali resistance, corrosion resistance, fingerprint resistance, lubricity, and properties to adhere to a topcoating film to a steel sheet plated with a zinc-or aluminum-contg. metal. CONSTITUTION:A water-base surface treatment fluid contg. a water-base ethylene- or urethane-base ionomer resin and hexavalent chromium ions in an amt. of 0.1-5wt.% of the solid content of the resin and having a pH adjusted to 7-11 is applied to a steel sheet plated with a zinc- and/or aluminum-contg. metal and is dried to form a resin film with a dry wt. of 0.3-5.0g/m<2>.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention applies a chromate-containing resin film treatment to a zinc- or aluminum-containing metal-plated steel sheet in a single step to obtain excellent alkali resistance, corrosion resistance, and
The present invention relates to a surface-treating composition, a surface-treating liquid, and a surface-treating method, which impart functions such as fingerprint resistance, lubricity, and adhesion of a top coat film.

[0002]

2. Description of the Related Art Conventionally, for the purpose of improving the corrosion resistance of a zinc- or aluminum-containing metal-plated steel sheet, a method of subjecting it to hexavalent chromium or a coating type chromate treatment containing hexavalent chromium and trivalent chromium is a treatment liquid component. It is recognized that it has the advantages that it is easy to maintain and manage, and can follow various plating types and line speed changes.
It has actually been adopted considerably. Further, in order to impart functions such as coating film adhesion and anti-fingerprint adhesion to the plated steel sheet, JP-A-58-224175 and JP-A-5-225
Disclosed in Japanese Patent Laid-Open No. 63-145785, etc., in which the reaction type, coating type or electrolytic type chromate treatment disclosed in Japanese Patent No. 20445 is applied to the plated steel sheet, and then a coating treatment with an organic resin is applied. A known method for coating a chromate-containing aqueous resin is known.

Among these conventional surface treatment methods, a single-step treatment method is a method capable of following the recent speeding up of the production line and imparting various functions to the zinc- or aluminum-containing metal-plated steel sheet. Chromate-containing water-based resin film treatment is promising. However, even in the chromate-containing water-based resin film treatment, as the line speed is increased, the drying temperature after the film treatment is inevitably lowered, which causes a problem that the film performance is deteriorated. In this way, the processing speed is increased, alkali resistance,
It is actually extremely difficult to simultaneously satisfy the functions such as corrosion resistance, lubricity, and coatability.

In recent years, 55% Al-Zn alloy plated steel has appeared as an excellent surface-treated steel sheet having long-term corrosion resistance. This 55% Al-Zn alloy plated steel sheet is said to have a life of 3 to 6 times that of the conventional hot-dip galvanized steel sheet, and its demand is in the fields of construction materials, industrial equipment, home appliances, automobiles, agriculture. The number of facilities is increasing. This 55
% Al-Zn alloy plated steel sheet has a composition in which the passivation film protective action of aluminum and the sacrificial anticorrosion action of zinc function in the most balanced manner, and the plating layer has an aluminum rich portion (segment). It has a tissue structure in which zinc-rich portions (segments) are surrounded by a mesh. Therefore, the plating layer of 55% Al-Zn alloy is different from the plating layer of the hot-dip galvanized steel sheet, and when corrosion starts, a dense and stable corrosion product (basic aluminum sulfate) is generated, which is a mesh-shaped space. It is said that it has excellent corrosion resistance because it is filled with to prevent the progress of corrosion. The 55% Al-Zn alloy plated steel sheet is said to have excellent corrosion resistance. However, it only takes a long time to generate red rust due to the corrosion of the base metal, and white rust is generated within a short period of time. It does not solve the problem that black rust occurs and impairs the beautiful appearance of silver white.
Therefore, it is considered necessary to carry out a coating treatment to solve the above problems.

Therefore, for the purpose of preventing the occurrence of white rust or black rust, a chromate treatment has been conventionally used, and a trace amount of hexavalent chromium was added to an aqueous resin containing a carboxyl group disclosed in Japanese Patent Publication No. 4-2672. Methods such as forming a resin film with the composition have been adopted. However, although the chromate-treated 55% Al-Zn alloy-plated steel sheet was able to improve its corrosion resistance,
In addition, it has a drawback that when it comes into contact with dissimilar metals, corrosion proceeds in a short period of time. On the other hand, the Japanese Patent Publication No. 4-2672
When a resin film layer is formed on the plating surface using the resin composition described in Japanese Patent Publication No. 1994-124, and the resin film layer contains hexavalent chromium, it is subjected to molding processing or the like. Even if this is done, it is possible to maintain considerable corrosion resistance.
However, if this resin coating layer contacts alkaline foreign substances such as mortar and concrete for a long time, it may cause a black discoloration (hereinafter referred to as black discoloration) on the surface as a phenomenon peculiar to aluminum, which may impair the appearance. It was Also, in fields other than the building materials field, 55% Al-Z
When n-alloy plated steel sheets are in practical use, for example, when used in household appliances such as washing machines and dryers that come into contact with detergents, hexavalent chromium in the film elutes, causing safety and health problems. Also, problems such as the above-mentioned black discoloration have been recognized.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a zinc- and / or aluminum-containing metal-plated steel sheet with alkali resistance, corrosion resistance, anti-fingerprint adhesion, lubricity, and low-temperature drying (baking) on existing high-speed lines. Another object of the present invention is to provide a surface-treating composition, a surface-treating liquid, and a surface-treating method capable of imparting a function such as adhesion of a top coat film.

[0007]

The present inventors have found that the object of the present invention can be achieved by using an ionomer resin as a means for solving the above-mentioned drawbacks of the prior art. Since the ionomer resin contains a carboxyl group, it has good adhesion to the article to be coated, and further has good solvent resistance because a part of the carboxyl group is crosslinked with a metal ion. The advantage is that the range of choice can be expanded. Furthermore, they have found that an ionomer resin whose main skeleton is ethylene-based or urethane-based is also effective for imparting lubricity. With such an ionomer resin as a main component, and containing hexavalent chromium ions,
When this is applied to an aluminum-containing plated steel sheet such as a 55% Al-Zn plated steel sheet, it exhibits excellent blackening resistance even when exposed to an extremely strong alkaline environment, and improves corrosion resistance. The present invention has been completed and the present invention has been completed.

The composition for surface treatment of a zinc- and / or aluminum-containing metal-plated steel sheet of the present invention comprises a resin component comprising at least one selected from ethylene ionomers and urethane ionomers, and the weight of the resin component. It is composed of an aqueous mixture containing 0.1 to 5% by weight of hexavalent chromium ions.

The above composition of the present invention may further contain a silicon compound. The above composition of the present invention may further contain an aqueous dispersion of polyethylene wax.

The surface treatment liquid for a plated steel sheet with a metal containing zinc and / or aluminum of the present invention contains the above-mentioned composition for surface treatment and has a pH of 7 to 11.

Further, the surface treatment method for a zinc- and / or aluminum-containing metal-plated steel sheet of the present invention comprises forming a treatment liquid layer comprising the above-mentioned surface treatment liquid on the surface of a plated steel sheet made of a zinc- and / or aluminum-containing metal. This is dried to form a chromate-containing resin film of 0.3 to 5.0 g / m ² .

[0012]

The present invention will be described in detail below. Ethylene ionomer water-based resin used in the present invention,
30 to 70% of the carboxyl groups contained in the copolymer of ethylene and acrylic acid or methacrylic acid, preferably 4
It has an ionomer structure in which 0 to 60% is intermolecularly associated or crosslinked with a metal ion such as sodium, potassium or zinc. As for the blending ratio of ethylene and acrylic acid or methacrylic acid, the weight ratio of ethylene / acrylic acid or methacrylic acid is preferably 2 to 18, and more preferably 4 to 9. If this weight ratio is less than 2, the content of the ethylene structure will be small, and the lubricity of the resulting coating may be insufficient. Further, when it exceeds 18, not only the content of the carboxyl group necessary for improving the adhesion between the obtained coating and the surface of the plating layer is insufficient, but also the water resistance of the obtained resin coating is lowered and Corrosion resistance may be insufficient. In addition, the association or cross-linking ratio of the carboxyl group by the metal ion is 30%.
If it is less than the above range, the resulting resin film may have insufficient properties such as alkali resistance and solvent resistance. On the other hand, if it exceeds 70%, the adhesion between the resin film obtained and the surface of the plating layer may be insufficient, and further the adhesion with the topcoat paint may be insufficient.

Further, the ionomer water-based resin used in the present invention includes a urethane ionomer resin. The method for producing the urethane ionomer resin is shown below. First, a prepolymer having NCO groups at both ends is synthesized by reacting a polyester and / or polyether-based polyol with an isocyanate. Next, the prepolymer is reacted with a carboxylic acid diol to synthesize an acid-modified prepolymer. Next, the acid-modified prepolymer is reacted with a metal ion such as sodium, potassium, or zinc, and 20 to 70%, preferably 40 to 60% of the carboxyl group of the acid-modified prepolymer is intermolecularly reacted with the metal ion. Allow to associate or crosslink. A basic substance such as triethylamine is added to the associated or crosslinked resin to ionically dissociate the free carboxyl group, and water is added to this to emulsify the resin in water. The NCO groups at both ends of this water-based prepolymer are polymerized by chain extension reaction with a diamine or the like to polymerize, thereby obtaining a urethane-based ionomer aqueous liquid useful in the present invention. The amount of the carboxyl group introduced into the resin skeleton by the carboxylic acid diol is preferably 30 to 150 as an acid value (AV). If this is less than 30, the aqueous carboxylation may be difficult due to a shortage of free carboxyl groups that are not associated or crosslinked with metal ions. Also it is 150
When it exceeds, the alkali resistance of the obtained resin film may be insufficient.

In the urethane-based water-based ionomer resin, by introducing a urethane bond, a urea bond or a buret bond into the resin skeleton, in addition to the above-mentioned characteristics of the ethylene-based ionomer resin, the strength of the obtained resin film is improved. It has the feature of significantly improving wear resistance. A polyether polyol used in its synthesis,
The types of polyester polyol, carboxylic acid diol and isocyanate are not particularly limited and may be appropriately selected from those usually used for the synthesis of urethane-based water-based ionomers, whereby sufficient association or cross-linking by the metal ion is possible. The effect can be obtained.

In the present invention, the use of hexavalent chromium ions is indispensable for obtaining a resin film having improved corrosion resistance and alkali resistance. Hexavalent chromium ions are generated from chromic acid or chromate compounds. Chromic acid is preferably used in the form of an aqueous solution of chromic anhydride, and the chromic acid salt is preferably selected from salts of chromic acid or dichromic acid such as ammonium, potassium, sodium and zinc. The amount of hexavalent chromium ions added is 0.1 to 5% by weight based on the weight of the ionomer resin component.
If this is less than 0.1% by weight, the corrosion resistance of the resin film obtained will be insufficient, and at the same time as the carboxyl group of the resin component,
The reaction with the valent chromium ions becomes insufficient, and the alkali resistance of the obtained resin film becomes insufficient. On the other hand, if it exceeds 5% by weight, the reaction rate becomes excessively high, and the useful life of the resin composition becomes insufficient.

A surface treatment solution is prepared from the above surface treatment composition. The surface treatment liquid preferably contains the ionomer resin component at a solid content concentration of 20 to 400 g / liter, and hexavalent chromium ions at a concentration of 0.03 to 10 g / liter. When the ionomer resin component solid content concentration is less than 30 g / liter, the weight (or thickness) of the obtained resin film may be insufficient,
On the other hand, if it exceeds 400 g / liter, the viscosity of the obtained surface treatment liquid becomes excessively high, and the coating appearance may be deteriorated due to roping or the like. Further, when the concentration of hexavalent ions is less than 0.03 g / liter, it is difficult to control the amount of chromium component in the obtained coating within an appropriate range with respect to the amount of resin component. There is
Further, if it exceeds 10 g / liter, the life of the obtained surface treatment liquid may be shortened, which may cause a disadvantage.

Furthermore, the pH of this surface treatment solution is 7-11.
Must be adjusted to. When the pH is less than 7, the chromic acid is insufficiently neutralized, the ionomer resin is easily oxidized, and the effective life of the surface treatment solution is shortened. When the pH exceeds 11, the zinc- and / or aluminum-containing metal plating layer is dissolved, which hinders molecular association or crosslinking during resin film formation, making it impossible to obtain desired performance. To adjust the pH of the surface treatment solution, it is preferable to use ammonia and volatile bases such as amines such as monoethylamine, diethylamine and triethylamine, and alkanolamines such as monoethanolamine, diethanolamine and triethanolamine.

The surface treatment liquid prepared as described above forms a surface treatment liquid layer on the surface of the zinc- and / or aluminum-containing metal-plated steel sheet by the method of the present invention. Zinc and / or aluminum-containing metal-plated steel sheet is mainly hot-dip aluminized steel sheet, hot-dip galvanized steel sheet, 5%
Al-Zn plated steel plate, 55% Al-Zn plated steel plate,
Includes galvannealed steel sheets, galvanized steel sheets, and the like. The present invention can also be applied to pure zinc materials and pure aluminum materials. Further, as the alloying element for zinc and / or aluminum, it is possible to use one or more of chromium, silicon, cobalt, zirconium, tin, titanium, iron, lead, nickel, magnesium, manganese, molybdenum, phosphorus and the like. it can.

In the method of the present invention, the dry weight of the surface treatment liquid is 0.3 to 5 g / on the surface of the plated steel sheet.
A surface treatment liquid layer of m ² is formed and dried to form a resin film. If the dry film weight is less than 0.3 g / m ² , the resulting resin film has insufficient alkali resistance, fingerprint adhesion resistance, corrosion resistance, lubricity, and coating adhesion, and
If it exceeds 5 g / m ² , the performance of the resin film obtained will be saturated, which will rather bring about an economic loss. As a method for forming the surface treatment liquid layer, a roll coater method, a spray coating method, a dipping air knife drawing method, or the like can be applied. In addition,
The degree of drying is sufficient if the water content of the surface treatment liquid layer is removed and a resin film is formed, but the ultimate plate temperature is preferably 60 ° C or higher. Surface treatment liquid layer, for example, 150 ℃
Although there is no problem even if it is dried at a high temperature as described above, in the production line of a predetermined length, the time required to reach the high temperature becomes long, which inevitably slows down the production line speed. , Productivity is reduced.

The surface treatment composition of the present invention has a corrosion resistance,
A silicon compound may be contained for the purpose of improving coating film adhesion. As the silicon-containing inorganic compound, silica having a primary particle size of 5 μm to 100 μm can be used. Such silica may be produced by either a gas phase method or a liquid phase method. The amount of silica added is preferably 30% or less based on the weight of the total solid content of the composition. If the silica content exceeds 30%,
The water resistance of the obtained resin film may decrease, and the corrosion resistance, alkali resistance, and coating film adhesion may become insufficient.

Examples of the silicon-containing organic compound include N-β
Amino group-containing silane coupling such as (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and γ-aminopropyltriethoxysilane Agents can be used.
The amount of the silane coupling agent added is preferably 10% or less based on the total solid content of the resin composition. If the amount added exceeds 10%, the silanol groups generated by the hydrolysis of the silane coupling agent may react with the resin composition and gelate easily, which is not preferable.

The surface-treating composition of the present invention may further contain an aqueous dispersion of polyethylene wax in order to impart a high degree of lubricity to the resulting resin film, for example, high speed deep drawing formability. The polyethylene wax used in the present invention is preferably one that is dispersed in water or an aqueous solution without using an emulsifier, and the blending amount thereof is a solid content weight ratio of 0.5 or less based on the total solid content weight of the water-based resin composition. It is preferable that If the blended solid content weight ratio of polyethylene wax exceeds 0.5, the strength of the resin film formed and the adhesion to the surface of the plating layer become insufficient, resulting in corrosion resistance, alkali resistance, solvent resistance, and formation of a top coating film. Adhesion and the like may be insufficient, and the lubricity may not be exhibited even if the content of the lubricating component is large.

Generally, an ionomer resin has a carboxyl group in its side chain, and a part of the carboxyl group has a structure in which molecular chains are associated or crosslinked with each other by a metal cation, and thus obtained. Gives the resin film excellent lubricity, adhesion to metals, etc., and chemical resistance. However, with the above structure alone, the corrosion resistance of the resin film obtained and the effect of preventing blackening on the aluminum-containing metal-plated steel sheet in a strongly alkaline environment are insufficient. Therefore, when a hexavalent chromium ion is contained in the ionomer resin, the hexavalent chromium ion reacts with the carboxyl group of the ionomer resin to make the resin film structure have a higher cross-linking density and to have alkali resistance, water resistance and solvent resistance. And the anti-sticking property of hexavalent chromium ions, it is possible to form a film with higher corrosion resistance. When such a chromate-containing resin film is formed in a single step on the surface of a zinc- and / or aluminum-containing metal-plated steel sheet, even when the aluminum-containing metal-plated steel sheet is contacted with a strong alkaline aqueous solution such as caustic soda, Also, the blackening can be prevented, and various excellent functions can be imparted to various zinc- and / or aluminum-containing metal-plated steel sheets.

[0024]

EXAMPLES In order to specifically explain the present invention, examples of applying the present invention to various plating materials are shown below,
And a comparative example is shown. Since the performance items required for each of the following materials differ depending on the type of the material, the following evaluation test was performed on each plated steel sheet.

Examples 1 to 18 and Comparative Examples 1 to 16 Table 1 shows the constitution and characteristics of the sample ionomer aqueous resin and the comparative aqueous resin having a non-ionomer structure. Tables 2, 3 and 4 show the processing conditions of the examples and comparative examples for the metal material under test. Ammonium dichromate was used as a source of hexavalent chromium ions blended in the water-based resin composition. In the coating-type chromate treatment of Comparative Example, Zinchrome-R1415A (trademark, manufactured by Nippon Parkerizing, composition; hexavalent chromium ion + trivalent chromium ion + silica) was applied and dried. The coating of the water-based resin composition and the coating type chromate solution was performed using a bar coater so that a predetermined adhesion weight was obtained after drying.

1. Metal Material A. In the case of electrogalvanized steel sheet Electrogalvanized steel sheet (Amount of coating: 20/20 g / m
² , oil-coated plate) was degreased with alkali, washed with water, dried, and then coated with the aqueous resin composition on the surface thereof under the treatment conditions of Examples 1 to 6 and Comparative Examples 1 to 5 shown in Table 2 and dried. . The test pieces sampled from the obtained steel sheet were subjected to evaluation tests of their flat surface corrosion resistance, fingerprint adhesion resistance, alkali resistance a (chromium fixing ratio) and lubricity a (deep drawability).

B. For 55% Al-Zn alloy plated steel sheet
If 55% Al-Zn alloy coated steel sheet (coating weight: 60
/ 60 g / m ² , non-oil coated plate) of Examples 7 to 7 shown in Table 3.
12, the aqueous resin composition was applied under the treatment conditions of Comparative Examples 6 to 12 and dried. The test pieces sampled from the obtained steel sheet were evaluated for alkali resistance b (blackening resistance), corrosion resistance at bent portions, sticking resistance and coating solution stability.

C. In the case of hot dip aluminum plated steel plate Hot dip aluminum plated steel plate (Amount of coating: 60/6
0 g / m ² , oil-free plate), and Examples 13 to 13 shown in Table 4 were used.
18, the water-based resin composition was applied under the treatment conditions of Comparative Examples 13 to 16 and dried. The test pieces collected from the obtained steel sheet were subjected to an evaluation test of their alkali resistance b (blackening resistance), sticking resistance, coating solution stability, top coating film adhesion and lubricity b (sliding property). .

2. Evaluation test method A. 3) Salt spray test according to JIS-Z-2371 was applied to the flat surface corrosion resistance test piece.
It was applied for 00 hours, and the result was visually evaluated according to the following evaluation criteria. Symbol White rust occurrence area rate ─────────────────── ◎ No white rust ○ White rust less than 10% △ White rust 10% to less than 30% × White rust 30% that's all

B. Anti-fingerprint Adhesion Resistance The finger surface was strongly pressed against the surface of the test piece, and the result of fingerprint trace formation was visually evaluated according to the following evaluation criteria. Code Fingerprint resistance ─────────────────── ○ Fingerprint traces are not visible △ Fingerprint traces are slightly visible × Fingerprint traces are clearly visible

C. Alkali resistance a (Chromium fixation ratio) Specimen was coated with an alkaline degreasing agent (trademark: PALCLEAN-N3
64S, made by Nippon Parkerizing) at 2% concentration, 60
It was sprayed at 2 ° C. for 2 minutes, washed with water and dried. The chromium adhesion amount of the test piece before and after degreasing was measured by fluorescent X-ray, and from the measurement result, the chromium fixing rate [chromium fixing rate (%) = (chrome adhesion amount after degreasing / chromium adhesion amount before degreasing) x 100] was calculated and the result was evaluated according to the following evaluation criteria. Symbol Chromium fixing rate (alkali resistance) ───────────────────── ○ 95% or more △ 80% to less than 95% × less than 80%

D. Lubricity a (deep drawability) A test piece was subjected to a cylindrical deep draw test under the conditions of a blank diameter of 92 mm, a punch of 40 mm, and a wrinkle holding pressure of 1 to 2 tons, and the results were evaluated according to the following evaluation criteria. Code Lubricity (deep drawing) ────────────────────────────────── ◎ Wrinkle pressure 2 ton No omission, abnormal build-up of coating, etc. ○ No wrinkle pressing pressure, no abnormalities such as film build-up △ Wrinkle pressing pressure, 1 ton omission, film build-up abnormality × Wrinkle pressing pressure, 1 ton omission Without

E. Alkali resistance b (blackening resistance) The test piece was immersed in a 1% NaOH aqueous solution at 25 ° C, and the difference in lightness (ΔL) between the test piece before and after the immersion was measured using a color difference meter. I asked for the time it took. The results were evaluated according to the following evaluation criteria. Symbol Required alkali immersion time (blackening resistance) ──────────────────────── ◎ 6 hours or more ○ 3 to less than 6 hours △ 1-3 hours Less than less than 1 hour

F. The corrosion resistance test piece of the bent portion was bent inward at two locations (2T bending) and subjected to a salt spray test for 200 hours. The white rust generated in the bent portion was visually evaluated according to the following evaluation criteria. Symbol White rust occurrence area rate ───────────────── ◎ No white rust ○ White rust less than 10% △ White rust 10-30% × White rust 30% or more

G. Sticking resistance The test piece is cut into a size of 70 × 150 mm, burrs are removed from both sides, the target surfaces are stacked on top of each other, and a load of 70 kgf · cm is applied to this with a torque wrench, at 50 ° C.
The sample was exposed to the atmosphere for 24 hours, and the sticking occurrence result was evaluated according to the following evaluation criteria. No. Sticking resistance evaluation standard ───────────────────── ○ No adherence between target surfaces △ Some adherence between target surfaces × Strong adherence between target surfaces

H. The surface treatment liquid used for the stability test of the surface treatment liquid was left to stand in an air atmosphere at 40 ° C., and the number of days required for it to gel or precipitate was measured. The results were evaluated according to the following evaluation criteria. Symbol Coating solution stability ─────────────── ○ 2 weeks or more △ 1-2 weeks or less × less than 1 week

I. Adhesiveness of top coat film A melamine alkyd paint (Dainippon Paint Co., Ltd., Trademark: Dericon 700 White) is applied on one side of the test piece to a thickness of 20-
It was coated so as to have a thickness of 25 μm, and was baked and dried. This coated plate was immersed in boiling water for 2 hours and then subjected to a coating film adhesion test. In this test, 100 squares of 1 mm square were engraved on one side of the test piece and pushed out by 5 mm using an Erichsen tester. Then, tape peeling was applied to this test surface, and the number of remaining marks of the coating film was measured. The results were evaluated according to the following evaluation criteria. Symbol Number of remaining coating film ───────────────── ◎ 100 ○ 91-99 △ 81-90 × 80 or less

J. The lubricity b (sliding property) test piece was subjected to a Bowden tester to measure the friction coefficient of the outermost layer of the coating, and the result was evaluated according to the following evaluation criteria. Code Coefficient of friction ───────────────── ◎ Less than 0.1 ○ 0.1 to less than 0.2 △ 0.2 to less than 0.4 × 0.4 or more

3. Evaluation test results In the case of electrogalvanized steel sheet in Table 2, 55% Al-in Table 3
In the case of a Zn-plated steel sheet, Table 4 shows the evaluation test results of Examples and Comparative Examples in the case of a hot-dip aluminum-plated steel sheet.

[0040]

[Table 1]

[0041]

[Table 2]

[0042]

[Table 3]

[0043]

[Table 4]

According to the present invention, the surface treatment liquid is an ethylene-based ionomer water-based resin having a solid content concentration of 20 to 400 g / liter or a urethane-based ionomer water-based resin under the production conditions of the test plates of Examples 1 to 17 respectively. When,
It contains hexavalent chromium ions in a weight ratio of 0.1 to 5% with respect to the solid content of the resin component, and has a pH of 7 to 11
It was adjusted to. This surface treatment liquid was applied onto both surfaces of a zinc- and / or aluminum-containing metal-plated steel sheet, and after drying, a resin coating having a coating amount of 0.3 to 5.0 g / m ² was formed. In Examples 1 to 17, each of the obtained chromium-containing resin-coated plated steel sheets exhibited excellent performance. The test plate production conditions of Comparative Examples 1 to 16 are:
The sample obtained under the conditions that do not correspond to the present invention,
Any one of them was insufficient in the performance of 1 or more.

In Examples 4, 8, 9, 10, 12, 15 and 16, since the surface treatment liquid further contains a silicon compound, the obtained resin-coated plated steel sheet has particularly high corrosion resistance and coating adhesion. Was excellent. Examples 3, 4, 1
In Nos. 0, 14 and 18, the surface treatment liquid further contained a polyethylene wax aqueous dispersion, and the obtained resin film was particularly excellent in lubricity.

[0046]

Industrial Applicability According to the present invention, zinc- and / or aluminum-containing metal-plated steel sheets have excellent alkali resistance,
A chromate-containing resin film having corrosion resistance, fingerprint resistance, lubricity, and adhesion of top coating film can be applied in a single step.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication C09D 5/00 PPK 5/08 PPX PQA PQE 175/00 PHW C23C 22/28

Claims (5)

[Claims] 1. A resin component comprising at least one selected from ethylene ionomers and urethane ionomers, and 0.1 to 5% by weight based on the weight of the resin component.
6. A composition for surface treatment of a zinc- and / or aluminum-containing metal-plated steel sheet, which comprises an aqueous mixture containing the hexavalent chromium ion. 2. The composition according to claim 1, further comprising a silicon compound. 3. The composition according to claim 1, further comprising an aqueous dispersion of polyethylene wax. 4. A surface treatment liquid for a zinc- and / or aluminum-containing metal-plated steel sheet, which comprises the composition according to any one of claims 1 to 3 and has a pH of 7 to 11. 5. A treatment liquid layer comprising the surface treatment liquid according to claim 4 is formed on the surface of a plated steel sheet made of a zinc-containing metal or an aluminum-containing metal, and this is dried,
A surface treatment method for a zinc- and / or aluminum-containing metal-plated steel sheet, which comprises forming a chromate-containing resin film of 0.3 to 5.0 g / m ² .