JP2721292B2 - Aluminum-zinc alloy coated steel sheet treated with organic surface treatment agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum-zinc alloy plated steel sheet treated with an organic surface treating agent.

[0002]

2. Description of the Related Art Aluminum-zinc alloy-plated steel sheets are:
Aluminum is 4 to 75% by weight. Most of the remaining is zinc, and third is Si, Mg, Ce-La (Misch metal).
It is a steel plate plated with an alloy to which components are added in trace amounts.

At present, low-aluminum-zinc alloy-plated steel sheets plated with an alloy comprising 4 to 10% by weight of aluminum, about 0.1% by weight of Mg and Ce-La, and the balance being zinc are commercially available. And a high aluminum-zinc alloy plated steel sheet plated with an alloy containing 55% by weight of aluminum, 43.4% by weight of zinc, and 1.6% by weight of Si. As for the corrosion resistance, when compared with the conventional hot-dip galvanized steel sheet with the same plating thickness, the corrosion resistance of the low aluminum-zinc alloy coated steel sheet is 1.5 to 2 times, and that of the high aluminum-zinc alloy coated steel sheet is 3 to 6 times. It has excellent properties. Due to this excellent corrosion resistance, it is widely used as a building material product such as roofing material and wall material, a material for civil engineering products such as guardrails, soundproof walls, drainage ditches, a material for bicycles, home appliances, industrial equipment, etc., and a substrate of painted steel plate. It is used. However, in aluminum-zinc alloy-plated steel sheets, since the plating layer contains aluminum, the following problems, especially in high aluminum-zinc alloy-plated steel sheets, compared to conventional galvanized steel sheets. Exists.

(1) When placed in a humid environment while being plated, rust is generated although the amount is smaller than that of a galvanized steel sheet. The rust is white in the galvanized steel sheet, but is gray to black in the aluminum-zinc alloy plated steel sheet, the plating surface is blackened, and the commercial value is significantly reduced. In order to solve this, conventionally, a chromate treatment is performed on the aluminum-zinc alloy plating layer.

(2) Compared with the conventional hot-dip galvanized steel sheet, the coating film is harder and has poor lubricity when processed by roll forming or press forming. A phenomenon that the plating layer is fused to a forming roll or a press die may occur. As a result, the metal powder from the aluminum-zinc alloy-plated steel sheet adheres to the forming rolls and press dies, and the metal powder accumulates at the corners of the formed product, causing seizure, scratches, abrasion, etc. Or a change in appearance. Conventionally, a lubricant such as oil or wax is applied to the surface of an aluminum-zinc alloy-plated steel sheet to solve this problem. However, when using aluminum-zinc alloy-plated steel sheets as roofing materials, there is a danger of slipping during construction, and in consideration of applying paint on this, the lubricant must be completely removed before shipping. No. In order to eliminate the trouble of applying and removing such a lubricant, a method of coating the surface of an aluminum-zinc alloy-plated steel sheet with an acrylic resin has been proposed. In this method, the chromate treatment described in (1) can be replaced by simultaneously adding chromic acid to the acrylic resin (Japanese Patent Publication No. 1-53353, Japanese Patent Publication No. 4-26).
72).

[0006]

However, the use of aluminum-zinc alloy-plated steel sheets has expanded, and
When used in construction products such as wall materials, civil engineering products such as guardrails, soundproof walls, drains, etc., they often come into contact with materials containing alkali metals or alkaline earth metals such as slate and concrete, and from these, alkali components Elutes, the surface of the aluminum-zinc alloy-plated steel sheet is significantly blackened by the influence of the alkali component, and the appearance is deteriorated,
If it is severe, it will be unusable.

An object of the present invention is to provide an aluminum-zinc alloy-plated steel sheet having alkali resistance, black rust resistance (corrosion resistance) in a humid environment, and lubricity.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a resin containing one or a mixture of two or more of a water-dispersible or water-soluble polyester resin or a water-dispersible or water-soluble polyurethane resin; 30% hexavalent chromium
The chromium compound containing above is 0.1 to 5 in terms of chromium oxide.
% Of the aluminum-zinc alloy-coated steel sheet is applied to the surface of the aluminum-zinc alloy-plated steel sheet at a dry weight of 0.3 to 4 g / m ^2. -Zinc alloy plated steel sheet.

[0009]

[0010]

[0011]

Further, the present invention provides a resin composition comprising a resin having a glass transition temperature of 40 ° C. or more and a resin having a glass transition temperature of less than 40 ° C. in a dry weight ratio excluding a chromic acid compound of 95: 5 to 50. : 50 is a mixture containing at a ratio of 50.

Further, the present invention provides the above-mentioned resin composition,
In addition, 0.1 to 20 parts by weight of olefin wax
%.

[0014]

The present inventors have conducted intensive studies and have obtained an aluminum-zinc alloy-plated steel sheet having a synthetic resin film having excellent alkali resistance and excellent corrosion resistance and lubricity in a humid environment. The properties of the synthetic resin film are related to the skeleton of the resin, the type of the functional group, the film thickness, and the like.

According to the present invention, the polyester resin or the polyurethane resin as the resin component forming the synthetic resin film has good alkali resistance, and is preferably water-dispersible or water-soluble from the viewpoint of recent VOC regulations and the like. .
The thickness of the resin is preferably thicker in consideration of alkali resistance, but the thicker the film, the longer it takes to dry and seize.
Insufficient seizure results in insufficient film formation, rather poor alkali resistance and high cost. Therefore, the amount of the resin film used in the present invention is 0.3 g / m ² (the same applies to the dry weight or less), and has a corrosion resistance effect equal to or more than 1 g / m ² of the conventional acrylic resin. Further, when plating and painting are processed on the same production line as the conventional one, it is not necessary to make the amount more than 4 g / m ² .

The polyester resin and the polyurethane resin are
0.3 to 4 g / m in the sense of having a lubricity equivalent to or higher than that of an acrylic resin, covering the surface of an aluminum-zinc alloy-plated steel sheet, and completely forming a film.
² is preferable, and is preferably 0. 0 in view of performance and cost.
It may be 8 to 1.5 g / m ² . Further, for special deep drawing applications, it is preferable to add 0.1 to 20% by dry weight of a polyolefin-based wax to the polyester resin or polyurethane resin coating in order to facilitate the processability. When the amount of the polyolefin-based wax is 0.1% or less, the effect is small, and when the amount is large, the processability is improved, but when it exceeds 20%, the corrosion resistance and the alkali resistance are reduced.

In order to impart corrosion resistance to the synthetic resin film,
It is necessary to incorporate a chromic acid compound. After performing chromate treatment on an aluminum-zinc-plated steel sheet, there is also a method of applying a coating of a polyester-based resin or a polyurethane-based resin, but assuming a real line, after performing a chromate treatment on the aluminum-zinc alloy-plated steel sheet, In the method of applying a resin film, the temperature of the steel strip rises due to drying after the chromate treatment, so that it becomes very difficult to control the application of the resin. Therefore, according to the present invention, the aluminum-zinc plated steel sheet is not subjected to the chromate treatment, but is coated with the resin component having the above-described composition containing hexavalent chromium. The hexavalent chromium in the resin is reduced to one part trivalent chromium during burning. The proportion of hexavalent chromium in the total chromium in the resin of the present invention is 30% or more. In the present invention, particularly when it is necessary to prevent the elution of hexavalent chromium, a reducing agent such as glycol is used, and the proportion of hexavalent chromium in the resin film is reduced to 30%.
%. The ratio of the chromium compound to be added to the resin is preferably 0.1 to 5% in terms of CrO _{3 with} respect to the solid content of the resin. If CrO ₃ is less than 0.1%, sufficient corrosion resistance is not exhibited. On the other hand, if it is more than 5%, the alkali resistance decreases and the stability of the resin composition deteriorates. The chromium compound used in the present invention is Cr
It is not particularly limited as long as it is a hexavalent chromium compound such as O ₃ , K ₂ CrO ₄ , K ₂ Cr ₂ O ₇ .

[0018]

The polyester resin and the polyurethane resin used in the present invention have different resin film hardness depending on the type. The higher the coating hardness, the better the lubricating performance on a flat surface, but when processed, fine cracks are generated in the processed part, so that the alkali resistance and corrosion resistance in the processed part are reduced. Therefore, in the present invention, the glass transition temperature (Tg)
Is as high as 80 to 40 ° C, and the resin and Tg with high coating hardness are
It is preferable that a resin having a low coating hardness of as low as less than 40 to -10 ° C is used in a dry weight ratio of 95: 5 to 50:50. In general, a resin having a low Tg is inferior in alkali resistance, corrosion resistance, and lubricity on a flat surface, but this results in a resin film excellent in alkali resistance, corrosion resistance, and lubricity of a flat portion and a processed portion.

[0020]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto.

Examples 1 to 10 As an aluminum-zinc alloy-plated steel sheet not subjected to a chromate treatment, the thickness is 0.6 mm, and the composition of the plating layer is Al.
= 55%, Zn = 43.4%, Si = 1.6% (all in weight%) and a plating adhesion amount of 75 g / m ² on one side. The size of the test piece was 250 mm x 50 mm for the hat-shaped bead-forming test, and 15 mm for the other tests.
0 mm × 75 mm was used.

On the other hand, the resin composition was prepared by adding water to 250 g of a polyester resin or polyurethane resin having a glass transition temperature shown in Table 1 and 2.5 g of chromium oxide containing 50% of hexavalent chromium with respect to all chromium. 1 kg, and immersed in a Parker Rising Co., Ltd. Pal cleaner for 30 seconds to prepare a resin aqueous solution or a resin aqueous dispersion. A bar coater No. is applied to the surface of the aluminum-zinc alloy-plated steel sheet obtained by degreasing the resin aqueous solution or the resin aqueous dispersion.
Using No. 5 to No. 20, coating was performed so that the dry coating amount was 2 g / m ² . Thereafter, the film was immediately placed in a hot-air drying oven at 500 ° C. for 5 seconds to form a dry film. The plate temperature at this time was 70 ° C. This was cooled to obtain a test plate. In addition, it was confirmed that the film thickness was 2 g / m ² by measuring the weight of the test piece before and after coating.

[0023]

[Table 1]

The test pieces obtained were tested for workability, corrosion resistance, alkali resistance, corrosion resistance and alkali resistance of the processed part, and color tone of the coating. Table 2 shows the results.

Comparative Examples 1 to 3 As resin compositions, acrylic resins (1) shown in Table 1 were used.
(Manufactured by Chuo Rika Kogyo Co., Ltd., trade name ES-20), acryl-styrene resin (manufactured by Asahi Kasei Corporation, trade name: Polytron F-2000) and acrylic resin (2) (manufactured by Toyobo Co., Ltd., product Name Tuftic FC-490) was used. The results of measuring the glass transition temperature of these resins are:
As shown in Table 1. Example 1 using these resins
Specimens of the same size were obtained in the same manner as in Test Nos. 1 to 10 and subjected to the same test. Table 2 shows the results.

[0026]

[Table 2]

Next, the test method will be described. This test method was similarly used in the following Examples and Comparative Examples.

(1) Workability Using a hat-forming tester 1 with a bead shown in FIG.
A test piece 11 of 0 mm × 50 mm is inserted between the table 3 and the presser 4 as shown in FIG. 1 and the punch 2 is moved 43 m at a speed of 70 mm / sec with the presser 4 lowered and the test piece 11 pressed.
m, a convex portion was formed on the test piece 11, and the test piece 11 was slid by the bead portion 5 of the table 3. FIG. 2 is a sectional view of the test machine 1 and the test piece 11 after processing, and FIG. 3 is a perspective view of the test piece 11 after forming processing. Evaluation of the test piece is performed by the following five-point method by visually observing the surface of the test piece.

5 No galling or pick-up in resin and metal 4 Slight galling occurred, 5 mg or less of resin and metal pickup 3 Slight galling occurred, 5-10 mg of resin and metal pickup 2 Galling considerably occurred, resin and metal Pickup 100mg 1 Processed part is broken and processing is not possible (2) Corrosion resistance Salt spray test with 5% saline solution 35 ° C × 400 hours (JIS Z 2371) Five-step evaluation by visual inspection of test piece 5 No white rust 4 White Rust generation rate less than 5% 3 White rust generation rate 5-10% 2 White rust generation rate 10-50% 1 White rust generation rate 50% or more (3) Alkali resistance 1% sodium hydroxide aqueous solution immersion test 30 ° C × 30
Minute 5-stage evaluation of test specimen visually 5 No black rust 4 Slight black rust is generated but not noticeable 3 Black rust is generated and slightly noticeable 2 Black rust is generated and the whole is black 1 Black rust is generated and the coating is very black, and a part of the coating falls off. (4) Corrosion resistance of the processed part A 150 mm × 75 mm test piece was D = 10 mm shown in FIG. 4 by a bending tester manufactured by Yasuda Seisakusho. A U-shaped test piece 12 of R = 5 mm was prepared, and 5% saline solution was sprayed at 35 ° C. for 400 hours on the outside of the bent surface (portion indicated by an arrow 13 in FIG. 3). I do.

The score is the same as the corrosion resistance of (2).

(5) Alkali Resistance in Processed Section A similar test piece was prepared in the same manner as in (4), and the bent surface was immersed in a 0.5% aqueous sodium hydroxide solution at 30 ° C. for 15 minutes, and the bent surface was visually observed. Is evaluated on a 5-point scale.

The rating is the same as the alkali resistance of (3).

(6) Color Tone of Coating The difference in color between the steel sheet and the base steel sheet is visually observed and evaluated in five levels.

5 Same color as the base steel plate 4 Slightly different color from the base steel plate 3 Appears slightly yellow 2 Appears quite yellow 1 Appears yellow From Examples 1-10 and Comparative Examples 1-3, polyester-based and polyurethane-based It can be seen that those using a resin are more excellent in alkali resistance of the non-processed portion and the processed portion than those using a conventional acrylic resin.

Example 11 As the resin components of the resin composition, the polyester resin (1) (glass transition temperature of 40 ° C. or more) and polyester resin (2) (glass transition temperature of less than 40 ° C.) in Table 1 were 95:
Examples 1 to 10 were used except that a mixture of 5 was used.
A test piece of the same size was obtained in the same manner as in Example 1 and the same test was performed. Table 3 shows the results.

Example 12 As the resin component of the resin composition, the polyester resin (1) (having a glass transition temperature of 40 ° C. or more) and the polyester resin (2) (having a glass transition temperature of less than 40 ° C.) shown in Table 1 were 50:
Examples 1 to 1 were used except that a mixture of 50 and 50 was used.
A test piece of the same size was obtained in the same manner as in Example 0, and the same test was performed. Table 3 shows the results.

Example 13 As resin components of the resin composition, the polyester resin (1) (having a glass transition temperature of 40 ° C. or more) and the polyester resin (2) (having a glass transition temperature of less than 40 ° C.) shown in Table 1 were 40:
Examples 1 to 1 were used except that a mixture of 60 and 60 was used.
A test piece of the same size was obtained in the same manner as in Example 0, and the same test was performed. Table 3 shows the results.

Example 14 As resin components of the resin composition, polyester resin (2) shown in Table 1 (glass transition temperature of less than 40 ° C.), polyester resin (3) (glass transition temperature of 40 ° C. or more), and polyurethane resin (1) ) (Glass transition temperature 40 ° C or higher) and 3
Except that a mixture of 0:40:30 was used, a test piece of the same size was obtained by the same method as in Examples 1 to 10, and the same test was performed. Table 3 shows the results.

[0039]

[Table 3]

From the results of Examples 1 to 14, it was found that the alkali resistance was slightly inferior to those using only a resin having a glass transition temperature of less than 40 ° C. and those having a ratio of 50% or more. On the contrary, it is understood that the alkalinity is inferior to those using only a resin having a glass transition temperature of 40 ° C. or higher. However, a resin having a glass transition temperature of 40 ° C.
５０50%, and a resin having a glass transition temperature of less than 40 ° C.
It can be seen that mixing by 50% improves the alkali resistance of the non-processed portion and the processed portion.

Examples 15 to 17 The polyester resin (1) shown in Table 1 was used as the resin component of the resin composition, and the chromium oxide to be added was changed when the ratio of hexavalent chromium to all chromium was 30% or more. Except having changed as described above, test pieces of the same size were prepared in the same manner as in Examples 1 to 10, and the same test was performed. The results are shown in Example 1.
The results are shown in Table 4 together with the results.

Comparative Example 4 The polyester resin (1) shown in Table 1 was used as the resin component of the resin composition, and the chromium oxide to be added was changed so that the ratio of hexavalent chromium to all chromium was less than 30% (20%). Other than that, test pieces of the same size were prepared in the same manner as in Examples 1 to 10, and the same test was performed. Table 4 shows the results.

[0043]

[Table 4]

From Table 4, it can be seen that when the ratio of hexavalent chromium to the total chromium is less than 30%, the corrosion resistance of the unprocessed portion and the processed portion is poor.

Examples 18 and 19 The polyester resin (1) shown in Table 1 was used as the resin of the resin composition, and the amount of chromium oxide added to the resin was 0.75 to 12.5 g shown in Table 5 (resin solid content ratio). 0.3 to 5
%), The same test was performed by preparing test pieces of the same size in the same manner as in Examples 1 to 10. Table 5 shows the results together with the results of Example 1. Further, in order to examine the stability of the resin composition containing chromium oxide, the prepared resin composition was left for one week, but there was no change in the resin composition.

Comparative Examples 5 and 6 The polyester resin (1) shown in Table 1 was used as the resin of the resin composition, and the amount of chromium oxide added to the resin was 0.75 g and 12.5 g shown in Table 5 (resin solid content ratio). 0.3
% And more than 5%).
Test pieces of the same size were prepared in the same manner as in Example 10 and subjected to the same test. Table 5 shows the results. In Example 18,
In order to examine the stability of the resin composition in the same manner as in Step 19, the prepared resin composition was left for one week. as a result,
In Comparative Example 5 in which the amount of chromium oxide added was small, there was no change in the resin composition, but in Comparative Example 6 in which the amount of chromium oxide was large, precipitation of chromium oxide occurred. Furthermore, the resin composition containing 10% or more of chromium oxide at a resin solid content ratio gelled after one week and became unusable.

[0047]

[Table 5]

From the above, it can be seen that the resin composition containing less than 0.3% or more than 5% of chromium oxide has inferior corrosion resistance in the non-processed portion, and the perchromic resin containing more than 5% of chromium oxide has no corrosion in the non-processed portion. It can be seen that the alkali resistance and the corrosion resistance of the processed part are inferior, and the color tone of the coating is also poor. When the amount of chromium oxide added is large, precipitation tends to occur with the passage of time, but when it is 5% or less, precipitation does not occur even after one week, indicating that the resin composition is stable.

Examples 20 and 21 The polyester resin (1) shown in Table 1 was used as the resin of the resin composition, and the thickness of the resin applied to the test piece was 0.3 to 4 g / m ² shown in Table 6. Other than the above, Examples 1-1
Specimens of the same size were prepared in the same manner as in Test No. 0 and subjected to the same test. Table 6 shows the results together with the results of Example 1.

Comparative Examples 7 and 8 The polyester resin (1) shown in Table 1 was used as the resin of the resin composition, and the thickness of the resin applied to the test piece was less than 0.3 g / m ² shown in Table 6 (0. 1 g / m ² ) or 4 g / m
Examples 1 to 1 except that the thickness was more than ² (5 g / m ² )
Specimens of the same size were prepared in the same manner as in Test No. 0 and subjected to the same test. Table 6 shows the results.

[0051]

[Table 6]

From this, when the film thickness is less than 0.3 g / m ² , the corrosion resistance of the non-processed portion and the processed portion and the alkali resistance of the non-processed portion and the processed portion are inferior, and when the film thickness exceeds 4 g / m ^2. In some cases, it was found that the alkali resistance of the unprocessed portion and the processed portion was poor, and the color tone of the film was slightly poor.

Examples 22 and 23 The polyester resin (1) shown in Table 1 was used as the resin of the resin composition, and the olefin wax (trade name: Permarine RN, manufactured by Sanyo Chemical Industries, Ltd.) is shown in Table 7. Except that 0.1 to 20% was added at a resin solid content ratio, test pieces of the same size were prepared in the same manner as in Examples 1 to 10, and the same test was performed. Table 7 shows the results.

Comparative Example 9 As a resin of the resin composition, a polyester resin (1) shown in Table 1 was used, and an olefin-based wax (trade name: Permarin RN, manufactured by Sanyo Chemical Industries, Ltd.) was used. A test piece of the same size was prepared and subjected to the same test in the same manner as in Examples 1 to 10, except that an amount of more than 20% (25%) was added in a fractional ratio. The results are shown in Table 7 together with the results of Example 1 in which no olefin wax was added.

[0055]

[Table 7]

From this, it can be seen that the workability is slightly improved by the addition of the wax, but when the added amount exceeds 20%, the alkali resistance of the non-processed portion and the processed portion decreases.

Examples 24-26 Aluminum-zinc alloy-coated steel sheets obtained by subjecting test pieces to a thickness of less than 60 mg / m ² as shown in Table 8 (the conditions for aluminum-zinc alloy plating were as described in Examples 1-10).
The same test as in Examples 1 to 10 was performed using the polyester resin (1) shown in Table 1 as the resin of the resin composition. The results are shown in Table 8 together with the results of Example 1 without chromate treatment.

Comparative Example 10 An aluminum-zinc alloy-plated steel sheet (the conditions for aluminum-zinc alloy plating were the same as in Examples 1 to 10) in which a test piece was chromate-treated to a thickness of 60 mg / m ² shown in Table 8 was used. Using the polyester resin (1) shown in Table 1 as the resin of the resin composition, test pieces of the same size were prepared in the same manner as in Examples 1 to 10, and the same test was performed. The result is
Table 8 shows the results of Example 1 without chromate treatment.

[0059]

[Table 8]

From this, it is understood that the corrosion resistance or alkali resistance of the processed portion is slightly deteriorated if the thickness of the chromate treatment is small or not. Conversely, when the thickness of the chromate treatment is 60 mg / m ² or more, the color tone of the coating becomes poor.

[0061]

As described above, according to the present invention, a one-layer treatment in which the surface is treated with a polyester resin or a polyurethane resin containing a chromic acid compound is excellent in workability, alkali resistance and corrosion resistance, and its color tone Also, a surface-treated aluminum-zinc alloy-plated steel sheet equal to or more than the conventional product can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a hat-equipped hat tester 1 for testing the workability of a test piece 11;

FIG. 2 is a cross-sectional view showing a state where a test piece 11 has been processed by a hat tester 1 with a bead.

FIG. 3 is a perspective view of a test piece 11 processed and formed by the hat-equipped hat tester 1;

FIG. 4 is a cross-sectional view of a test piece 12 for testing the corrosion resistance of the processed portion and the alkali resistance of the processed portion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hat test machine with a bead 11 Test piece for workability 12 Test piece for corrosion resistance and alkali resistance in a processed part

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Yoshihiko Hobo 1850 Minato, Wakayama, Wakayama Sumitomo Metal Industries, Ltd.Wakayama Works (72) Inventor Hiroshi Fukudome, 1850 Minato, Wakayama, Wakayama Sumitomo Metal Industries In-house (72) Inventor Naotaka Ueda 1850 Minato, Wakayama-shi, Wakayama Prefecture Sumitomo Metal Industries, Ltd. Wakayama Works (56) References JP-A-4-28878 (JP, A) JP-A-5-65667 (JP, A)

Claims (3)

(57) [Claims] 1. A resin component containing one or more of a water-dispersible or water-soluble polyester resin or a water-dispersible or water-soluble polyurethane resin, and 30% or more of hexavalent chromium based on the resin component. A chromium compound containing 0.1 to 5% in terms of chromium oxide is coated on the surface of an aluminum-zinc alloy-plated steel sheet with 0.3 to 4%.
An aluminum-zinc alloy-plated steel sheet treated with an organic surface treating agent, wherein the aluminum-zinc alloy sheet is applied at a dry weight of g / m ² . 2. The method according to claim 1, wherein the resin composition has a glass transition temperature of 40.
C. or more and a resin having a glass transition temperature of less than 40 ° C.
95: 5-5 by dry weight ratio excluding the chromic acid compound
The aluminum-zinc alloy-plated steel sheet treated with the organic surface treating agent according to claim 1, wherein the mixture is a mixture containing 0:50. 3. The aluminum treated with an organic surface treating agent according to claim 1, wherein the resin composition further contains 0.1 to 20% by dry weight of an olefin-based wax. -Zinc alloy plated steel sheets.