JP2001348676A - Recoated steel sheet and its production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively provide a precoated steel sheet having excellent designing properties without deteriorating spangle patterns characteristic of an aluminum-zinc alloy plated steel sheet largely containing an aluminum component in the plating layer and brightness and color tones appendent thereto and also excellent in corrosion resistance, alkali resistance, scratch resistance, or the like. SOLUTION: This precoated steel sheet is produced by forming a chemical conversion film on the surface of an aluminum-zinc alloy plated steel sheet having an aluminum-zinc alloy plating layer in which the content of aluminum is 40 to 70 wt.% and forming only one resin layer having a film thickness of 2 to 15 μm thereon. The resin layer contains flaky pearl pigment whose average length in the long side direction is <=50 μm by 0.1 to 20 pts.wt. to 100 pts.wt. of the resin solid content, and the chemical convention film is preferably a thin film containing an organic resin and phosphoric acid or/and a phosphoric compound and chromic acid or/and partially reduced chromic acid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated steel sheet having excellent corrosion resistance and design properties and suitable for applications such as construction, home appliances, and automobiles. In addition, the coated steel sheet can be used as a steel sheet for kitchens as a substitute for a stainless steel sheet having high designability.

[0002]

2. Description of the Related Art A chemically treated steel sheet having an aluminum-zinc alloy-plated steel sheet containing a large amount of an aluminum component in a plating layer and having an organic thin film containing chromic acid and an acrylic resin and having a thickness of about 1 μm formed on the surface thereof is used as a non-painted material. It is used mainly for building materials because it shows good corrosion resistance. In addition, this coated steel sheet is popular in the market for its spangle pattern peculiar to aluminum-zinc alloy plating containing a large amount of aluminum in the plating layer and its design (brightness) accompanying the spangle pattern. However, the corrosion resistance of the coated steel sheet is hardly sufficient compared with the coating material. Also, if it comes in contact with cement, etc.
The environment becomes high pH, aluminum in the plating elutes, and corrosion occurs early.

[0003] As a means for improving the corrosion resistance without impairing the spangle pattern of the aluminum-zinc alloy-plated steel sheet, it is conceivable to apply a clear coating as a means for improving the corrosion resistance. There is a disadvantage that the coating is easily formed, the plating is exposed from that portion, and corrosion proceeds.

Japanese Patent Application Laid-Open No. 63-7937 discloses that
As a colored coated steel sheet utilizing the spangle pattern of an aluminum-zinc alloy-plated steel sheet, a steel sheet in which a plating layer surface is coated with a colored resin having a predetermined concealment ratio has been proposed. The purpose of this is to suppress by coloring, and there is a disadvantage that the design property is impaired by the spangle pattern.

[0005] On the other hand, a coating material is produced by coating and baking an undercoat and an overcoat on a plated steel sheet. Although this coating material has better corrosion resistance than the non-coating material, the two-coat method complicates the manufacturing process and increases the cost. Further, even in a coated steel sheet subjected to a skin pass treatment, irregularities derived from the spangle pattern emerge on the surface of the coating film, and a poor appearance is obtained particularly in a coating film having a high glossiness.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an excellent spangle pattern peculiar to an aluminum-zinc alloy-plated steel sheet containing a large amount of an aluminum component in a plating layer and an excellent brightness and color tone accompanying the spangle pattern. An object of the present invention is to provide a coated steel sheet having a design property and excellent in corrosion resistance, alkali resistance, scratch resistance, etc. at low cost.

[0007]

Means for Solving the Problems A coated steel sheet and a method of manufacturing the same according to the present invention for solving such problems have the following features.

[1] A chemical conversion coating is formed on the surface of an aluminum-zinc alloy-plated steel sheet having an aluminum-zinc alloy plating layer having an aluminum content of 40 to 70% by weight, and a film having a thickness of 2 to 15 μm is formed thereon. A coated steel sheet in which only one resin layer is formed, wherein the resin layer is scale-like and has an average length in the long side direction of 50 μm or less. A coated steel sheet characterized by containing a part thereof.

[2] In the above [1], the chemical conversion treatment film is
A coated steel sheet comprising a thin film containing an organic resin, phosphoric acid or / and a phosphoric acid-based compound, and chromic acid and / or partially reduced chromic acid.

[3] After forming a chemical conversion coating on the surface of an aluminum-zinc alloy-plated steel sheet having an aluminum-zinc alloy-plated layer having an aluminum content of 40 to 70% by weight, a scaly and long flake is formed on the upper surface thereof. After applying a coating composition containing 0.1 to 20 parts by weight of a pearl pigment having an average length in the side direction of 50 μm or less with respect to 100 parts by weight of the resin solid content so that the dry film thickness becomes 2 to 15 μm, 180 ~
A method for producing a coated steel sheet, comprising baking at an ultimate sheet temperature of 260 ° C.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below together with the reasons for limiting the same.

The coated steel sheet of the present invention is a coated steel sheet in which a chemical conversion coating is formed on the surface of an aluminum-zinc alloy-plated steel sheet, and a single resin layer containing a specific component is formed thereon.

The aluminum-zinc alloy-plated steel sheet serving as the base steel sheet is a plated steel sheet having an aluminum-zinc alloy plating layer containing 40 to 70% by weight of aluminum. Here, the aluminum content in the plating layer is 40
If it is less than 70% by weight or less than 70% by weight, a beautiful spangle on the plating surface cannot be obtained. That is, when the aluminum content is less than 40% by weight, a uniform gray black like a hot-dip galvanized steel sheet is obtained, and when the aluminum content exceeds 70% by weight, a uniform silver-white appearance is obtained. Also, from the viewpoint of corrosion resistance, the aluminum content is 40 to 70.
A range of weight% is preferred.

Further, in the case of an aluminum-zinc alloy coated steel sheet in which the plating layer is composed of only 40 to 70% by weight of aluminum and zinc, an excessive alloying reaction occurs between Fe and Al of the base steel sheet and the adhesion of the plating layer Therefore, usually 3% by weight in the plating layer is used to suppress alloying.
It contains the following amount of Si.

If the average diameter of the spangle on the plating surface is less than 0.01 mm, it cannot be sufficiently recognized as a spangle, so the average diameter is preferably 0.01 mm or more. Further, in order to make the spangle look clearer, the average diameter is preferably 0.3 mm or more. The average diameter of the spangle is 10 cm × 10
arbitrarily selected 10 places from a steel sheet sample of 1 cm
When the number of spangles crossing the length of m is counted, [average diameter of spangle] (unit: mm) = 100 /
It is defined as [sum of count values of 10 places].

The chemical conversion coating formed on the surface of the aluminum-zinc alloy plated steel sheet is not particularly limited.
For example, a phosphate treatment film, a chromate treatment film, an organic resin thin film and the like can be applied, but from the viewpoint of forming a film having excellent adhesion and excellent appearance uniformity, as a chemical conversion treatment film, Organic resin and phosphoric acid or /
It is preferable to form a thin film containing (and preferably containing, as a main component) a phosphoric acid compound and chromic acid and / or partially reduced chromic acid.

Of these components of the chemical conversion coating, chromium acts as a binder for obtaining the adhesion to the plating layer, and the organic resin effectively acts on the adhesion to the upper coating. However, since the upper layer film has a low concealing property and the plating surface appearance can be seen through, phosphoric acid is necessary especially for beautiful appearance. Since the coloring of chromium or the like is suppressed by the addition of phosphoric acid, good adhesion can be obtained without impairing the appearance.

Next, the resin layer formed only on the upper part of the chemical conversion coating will be described.

The main resin used in the resin layer is not particularly limited, but an acrylic resin and / or a polyester resin are particularly preferable from the viewpoints of weather resistance, hardness, workability, and adhesion.

The acrylic resin contains at least two acrylic resins per molecule.
Number of hydroxyl groups and a number average molecular weight of 1500 to 20
000, the number average molecular weight is preferably in the range of 1700 to 10
000. Hydroxyl groups in the acrylic resin molecule are randomly arranged in the acrylic resin main chain, and when the number average molecular weight is less than 1500, the processability is significantly reduced. on the other hand,
When the number average molecular weight exceeds 20,000, the weather resistance is lowered and the viscosity becomes high, so that an excess of a diluting solvent is required, and the proportion of the resin in the coating material is reduced, so that an appropriate coating film cannot be obtained. Further, the compatibility with other compounding components is significantly reduced. The number average molecular weight of the acrylic resin is a molecular weight in terms of polyester measured by gel permeation chromatography (hereinafter, referred to as GPC).

The acrylic resin is a copolymer obtained by subjecting an acrylic monomer or methacrylic monomer having a hydroxyl group to an acrylic ester or a methacrylic ester by a known method. As the acrylic monomer and methacryl monomer having a hydroxyl group, for example, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate and the like can be used. Also,
As acrylic acid esters and methacrylic acid esters,
For example, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, methacrylic acid 2-ethylhexyl and the like can be used. Commercially available acrylic resins include "Almatex" (trade name, manufactured by Mitsui Chemicals, Inc.), "Desmophen" (trade name, manufactured by Sumitomo Bayer Urethane Co., Ltd.), and "Dianal" (trade name, manufactured by Mitsubishi) Rayon Co., Ltd.).

The polyester resin has at least two hydroxyl groups in one molecule and has a number average molecular weight of 1,000 to 1,000.
Although it is not particularly limited as long as it is a compound of 20,000, the preferable range of the number average molecular weight is 1200 to 1
0000, more preferably 1500 to 6000.
The hydroxyl group in the molecule of the polyester resin may be at either the terminal or the side chain in the molecule. If the number average molecular weight of the polyester resin is less than 1,000, the processability will be significantly reduced. On the other hand, if the number average molecular weight exceeds 20,000, the weather resistance is lowered and the viscosity becomes high, so that an excess dilution solvent is required, and the ratio of the resin in the coating material is reduced, so that an appropriate coating film can be obtained. Disappears. Further, the compatibility with other compounding components is significantly reduced. The number average molecular weight of the polyester resin is a molecular weight in terms of polystyrene measured by GPC.

The polyester resin is a copolymer obtained by heating and reacting a polybasic acid component and a polyhydric alcohol by a known method. As the polybasic acid component, for example, phthalic anhydride, isophthalic acid, terephthalic acid, trimellitic anhydride, maleic acid, adipic acid, fumaric acid and the like can be used. Further, as the polyhydric alcohol, for example,
Ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, triethylene glycol, glycerin, pentaerythritol, trimethylolpropane, tri Methylolethane or the like can be used. “Almatex” is a commercially available polyester resin.
(Trade name, manufactured by Mitsui Chemicals, Inc.), "alkynol" (trade name, manufactured by Sumitomo Bayer Urethane Co., Ltd.), "desmophen" (trade name, manufactured by Sumitomo Bayer Urethane Co., Ltd.), "Byron" (trade name) And Toyobo Co., Ltd.).

As a curing agent for the main resin, a polyisocyanate compound and / or an amino resin can be used.

As the polyisocyanate compound, an isocyanate compound obtained by a general production method can be used. Among them, phenol, cresol, aromatic secondary amine, Polyisocyanate compounds blocked with blocking agents such as tertiary alcohols, lactams, oximes and the like are preferred. By using this blocked polyisocyanate compound, storage with one liquid becomes possible, and use as a paint becomes easy.

More preferred polyisocyanate compounds include non-yellowing hexamethylene diisocyanate (hereinafter abbreviated as HDI) and its derivatives, tolylene diisocyanate (hereinafter abbreviated as TDI) and its derivatives 4,4'- Diphenylmethane diisocyanate (hereinafter abbreviated as MDI) and its derivatives, xylylene diisocyanate (hereinafter abbreviated as XDI) and its derivatives, isophorone diisocyanate (hereinafter abbreviated as IPDI) and its derivatives, trimethylhexamethylene diisocyanate (hereinafter abbreviated as TMDI) ) And its derivatives,
Examples include hydrogenated TDI and its derivatives, hydrogenated MDI and its derivatives, hydrogenated XDI and its derivatives, and the like.

Furthermore, "Sumijur" (trade name, manufactured by Sumitomo Bayer Urethane Co., Ltd.), "Desmodur" (trade name, manufactured by Sumitomo Bayer Urethane Co., Ltd.), "Coronate" (trade name, Nippon Polyurethane Co., Ltd.) )) Can also be used.

When a polyisocyanate compound is used as a curing agent, the compounding ratio of the isocyanate group of the polyisocyanate compound to the hydroxyl group in the base resin [NCO / O
H] is a molar ratio of 0.8 to 1.2, more preferably 0.9.
It is desirable to set it in the range of 0 to 1.10. [NCO /
When the molar ratio of [OH] is less than 0.8, curing of the coating film is insufficient, and desired coating film hardness and strength cannot be obtained. on the other hand,
When the molar ratio of [NCO / OH] exceeds 1.2, a side reaction occurs between excess isocyanate groups or between the isocyanate group and the urethane compound, and the processability of the coating film is reduced.

As the amino resin as a curing agent, urea,
Resins obtained by reacting benzoguanamine, melamine, etc. with formaldehyde, and those obtained by alkyl etherifying these with alcohols such as methanol and butanol can be used. Specifically, a methylated urea resin, n
-Butylated benzoguanamine resin, methylated melamine resin, n-butylated melamine resin, iso-butylated melamine resin, and the like.

Further, "Cymel" (trade name, manufactured by Mitsui Cyanamid Co., Ltd.), "Uban" (trade name, manufactured by Mitsui Toatsu Chemicals, Inc., "Sumimar" (trade name, manufactured by Sumitomo Chemical Co., Ltd.) ) And "Melan" (trade name, manufactured by Hitachi Chemical Co., Ltd.) can also be used.

When an amino resin is used as a curing agent, the blending ratio (weight ratio of solid content) of the amino resin and the base resin is [base resin] / [amino resin]: 95/5 to 65/3.
5, preferably 90/10 to 75/25.

The compounding amount of the curing agent is preferably 9 to 50% by weight in the resin solid content. If the amount of the curing agent is less than 9% by weight, the hardness of the coating film is insufficient, while if it exceeds 50% by weight, the processability is insufficient.

The resin layer contains a pearl pigment. Metallic powder can be considered as the photovoltaicity imparting material contained in the resin. Aluminum powder is generally used as the metal powder. When the aluminum powder comes into contact with cement or the like, the environment becomes high in pH, the aluminum powder elutes, and corrosion occurs early. The fact that corrosion is likely to occur when it comes in contact with cement is undesirable because it limits the use of painted steel sheets outdoors, and it has a moderate alkali resistance and a metallic luster. Pigments are optimal.

As the pearl pigment to be blended in the resin layer,
A scaly one having an average length in the long side direction of 50 μm or less is used. The use of scaly pearl pigments is because the pearl pigment plate-like crystal particles are regularly arranged in parallel and reflect light, and the reflected light causes interference and gives pearl luster to the metallic appearance. Because it is necessary.

If the average length of the flaky pearl pigment in the long side direction exceeds 50 μm, the surface of the coated steel sheet has too high brilliancy to utilize spangles on the surface of the coated steel sheet. Will fade. Also, if the average length in the long side direction of the pearl pigment is too small, the brilliancy of the surface of the coated steel sheet is weakened. Therefore, the average length in the long side direction of the pearl pigment is preferably 20 μm or more. The pearl pigment is selected from natural pearl essence, basic lead carbonate, bismuth oxychloride, lead arsenide hydrogen, titanium oxide-coated mica, iron oxide-coated mica, titanium oxide-iron oxide-coated mica, and other metal oxide-coated mica. Titanium oxide-coated mica, iron oxide-coated mica, titanium oxide-iron oxide-coated mica, and other metal oxide-coated mica are suitable in consideration of one of the objects, that is, inexpensive provision.

The amount of the pearl pigment in the resin layer is 0.1 to 20 parts by weight based on 100 parts by weight of the solid content of the resin. If the blending amount of the pearl pigment is less than 0.1 part by weight based on 100 parts by weight of the resin solid content, high design properties due to the pearl pigment will not be exhibited, and the scratch resistance will also decrease, which is not suitable. On the other hand, if the amount of the pearl pigment exceeds 20 parts by weight, the spangle pattern of the base plated steel sheet cannot be observed,
The spangle pattern peculiar to the aluminum-zinc alloy-plated steel sheet and its associated glitter and color tone are impaired. Also,
In order to more clearly observe the spangle of the plated steel sheet and to ensure better scratch resistance, the blending amount of the pearl pigment with respect to 100 parts by weight of the resin solid content is 2-1.
Preferably it is 2 parts by weight.

By blending the pearl pigment in the resin layer under the above conditions, it is possible to impart glitter to the coated steel sheet without impairing the high design property due to spangles peculiar to the aluminum-zinc alloy-plated steel sheet. And excellent in alkali resistance. Such effects cannot be obtained even if other metal powders or pigments are added. Further, the addition of the pearl pigment has an effect of further improving the scratch resistance of the resin layer.

In the resin layer, in addition to the above-mentioned pearl pigment, an appropriate amount of various pigments or metal powder for the purpose of coloring the film can be added. In particular, although aluminum powder has slightly reduced alkali resistance, by adding it, the color tone of the base-plated steel sheet is maintained without change, and excellent design properties can be obtained. The gloss can be adjusted by adding an inorganic or organic aggregate such as silica, glass fiber, or acrylic beads as a matting agent. Furthermore, a suitable amount of wax can be blended in the resin layer according to the purpose and application. As this wax, a natural wax or a synthetic wax can be used.

The thickness of the resin layer is 2 to 15 μm. If the film thickness is less than 2 μm, the corrosion resistance is not sufficiently improved, and the retention of the pearl pigment becomes difficult. On the other hand, if the film thickness exceeds 15 μm, observation of the spangle pattern becomes difficult and the cost increases, which is not preferable.

In actually using the coating composition for forming the resin layer, these are dissolved in an organic solvent before use. Examples of the organic solvent to be used include methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, Solvesso 100 (trade name, manufactured by Exxon Chemical Co., Ltd.),
Solvesso 150 (trade name, manufactured by Exxon Chemical Co., Ltd.), Solvesso 200 (trade name, manufactured by Exxon Chemical Co., Ltd.), toluene, xylene, methyl cellosolve, butyl cellosolve,
Cellosolve acetate, butyl cellosolve acetate,
Examples include carbitol, ethyl carbitol, butyl carbitol, ethyl acetate, butyl acetate, petroleum ether, petroleum naphtha and the like.

The coating composition for the resin layer may contain p-toluenesulfonic acid, tin octoate,
A curing catalyst such as dibutyltin dilaurate and lead 2-ethylhexoate, and various other additives such as an antifoaming agent and a flow stopper can be appropriately compounded.

In preparing the coating composition for the resin layer, a conventional disperser or kneader such as a sand grind mill, a ball mill, or a blender may be selected and used, and each component may be blended.

The method of applying the coating composition for forming the resin layer is not particularly limited, but preferably the coating composition is applied by a method such as roll coater coating or curtain flow coating. After applying the coating composition, baking the coating film by heating means such as hot air heating, infrared heating, induction heating,
The resin is crosslinked to obtain a resin layer. The baking treatment at the time of heat-curing the coating film is usually performed by setting the maximum reached plate temperature to 180 to 260.
C., and baking is performed in this temperature range for about 30 seconds to 3 minutes.

[0044]

EXAMPLE 100 parts by weight of polyester resin or acrylic resin as base resin, methylated melamine 2 as curing agent
5 parts by weight, 0.5 parts by weight of dibutyltin dilaurate as a curing catalyst, and flaky pearl pigment (titanium oxide-coated mica, average length in the long side direction of 25 μm) were blended in the proportions shown in Tables 1 and 2, The mixture was stirred for 1 hour with a sand mill to prepare a coating composition for a resin layer.

After forming a chemical conversion coating (film thickness: 1 μm) on each of the plated steel sheets shown in Tables 1 and 2, the coating composition was applied by a bar coater to a predetermined dry film thickness.
By baking at an ultimate temperature of the steel sheet of 220 ° C. and a baking time of 53 seconds, inventive examples 1 to 8 and comparative examples 1, 2, 8, 9
Was obtained.

In Comparative Example 3, a coated steel sheet containing no pearl pigment in the resin layer, in Comparative Example 4, a coated steel sheet having no chemical conversion coating, and in Comparative Example 7, a coated steel sheet containing aluminum powder were used. It was manufactured by the method according to. As Comparative Example 5, a surface-treated steel sheet on which only a chemical conversion coating was formed, and as Comparative Example 6, an epoxy-based primer (baking conditions: 220 ° C. × 38
Second, dried film thickness: 4 μm), and a coated steel sheet on which a polyester-based overcoating film (baking conditions: 230 ° C. × 53 seconds, dry film thickness: 13 μm) was formed.

The coated steel sheet and the surface-treated steel sheet were evaluated for spangle visibility, design property, corrosion resistance, scratch resistance, alkali resistance, and appearance by the following evaluation methods. The results are shown in Tables 1 and 2 together with the coating composition of each coated steel sheet and surface-treated steel sheet.

(1) Visibility Observed visually, and evaluated according to the following criteria.

◎: Spangles can be clearly seen. ス パ ン: Spangles patterns are slight but can be seen. △: Spangles patterns can hardly be seen. ×: Spangles cannot be seen at all. (2) Designability Observed visually and evaluated according to the following criteria. did.

：: There is a glittering feeling and metallic feeling ×: There is no glittering feeling and metallic feeling (3) Corrosion resistance For the test material, salt spray test SST (JIS Z 23)
The surface was observed after performing (71) for 1000 hours, and evaluated according to the following criteria.

：: No swelling or white rust is observed on the surface ×: Swelling or white rust is observed on the surface (4) Scratch resistance Peel hardness is measured by a pencil hardness test (JIS K 5400). And evaluated according to the following criteria.

◎: No peeling at 3H ○: No peeling at 2H △: No peeling at H ×: Peeling at H (5) Alkali resistance ○: No swelling after immersion in 5% NaOH aqueous solution for 24 hours ×: 5% Swelling is observed after immersion in NaOH aqueous solution for 24 hours. (6) Appearance ○: Appearance consisting only of plating surface and color tone of pearl pigment △: Appearance mainly consisting of plating surface and color tone of pearl pigment, but other colors There is a little influence. ×: The appearance is completely different from the plating surface and the color tone of the pearl pigment.

[0053]

[Table 1]

[0054]

[Table 2]

From Tables 1 and 2, it can be seen that, in the examples of the present invention, coated steel sheets excellent in all of visibility, design, corrosion resistance, scratch resistance, alkali resistance and appearance can be obtained.

On the other hand, in the comparative example, at least one of visibility, design, corrosion resistance, scratch resistance, alkali resistance, and appearance is inferior.

[0057]

As described above, according to the present invention, the spangle pattern peculiar to the aluminum-zinc alloy-plated steel sheet containing a large amount of aluminum component in the plating layer and the glitter and color tone accompanying the spangle pattern are excellent without being impaired. A coated steel sheet having a design property and excellent in corrosion resistance, alkali resistance, scratch resistance and the like can be obtained at low cost.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B32B 15/18 B32B 15/18 C23C 22/28 C23C 22/28 22/30 22/30 22/33 22 / 33 (72) Inventor Keiji Yoshida 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Takafumi Yamachi 1-2-1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. 72) Inventor Hiroshi Ishikawa F-term (reference) 4D075 BB26Z BB74Y BB75Y BB87X BB92Z BB93Z CA02 CA33 CA44 CA33 CA44 CB11 DA06 DB05 DB07 DC01 DC11 DC18 DC38 EA07 EB22 EB32 EB35 EB38 EB45 EC11 EC23 EC53 EC54 4F100 AA04B AA21 AA22 AA22B AB03A AB10A AB18A AB31A AC10 AK01B AK01C AK25 AK41 AR00B BA03 BA07 BA10A BA10C CA02 CA13C CC00C DE02C DE02H 462 EH71A EJ422 EJ68B EJ682 EJ69 GB07 GB08 GB32 GB48 JA20C JB01 JB02 JK14 JM02C JN22C YY00A YY00C 4K026 AA02 AA07 AA09 AA13 AA22 BA01 BA07 BA12 BB01 BB08 BB10 CA16 BA02 CA23

Claims (3)

[Claims] An aluminum content of 40 to 70% by weight
A coated steel sheet in which a chemical conversion treatment film is formed on the surface of an aluminum-zinc alloy-plated steel sheet having an aluminum-zinc alloy-plated layer, and only a single resin layer having a thickness of 2 to 15 μm is formed thereon. A coated steel sheet wherein the layer is flaky and contains 0.1 to 20 parts by weight of a pearl pigment having an average length in the long side direction of 50 μm or less based on 100 parts by weight of the resin solid content. 2. The coating according to claim 1, wherein the chemical conversion coating is a thin film containing an organic resin, phosphoric acid and / or a phosphoric acid compound, and chromic acid and / or partially reduced chromic acid. steel sheet. 3. An aluminum content of 40 to 70% by weight.
After a chemical conversion coating is formed on the surface of an aluminum-zinc alloy-plated steel sheet having an aluminum-zinc alloy-plated layer, a pearl pigment having a scale-like shape and an average length in the long side direction of 50 μm or less is formed on the resin solid. After coating the coating composition in an amount of 0.1 to 20 parts by weight with respect to 100 parts by weight per minute so that the dry film thickness is 2 to 15 μm,
A method for producing a coated steel sheet, comprising baking at an ultimate sheet temperature of 60 ° C.