JP2002307610A - Coated metal panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coated metal panel coated with a thick coating film good in hardness, processability, non-tackiness, blocking resistance or the like. SOLUTION: The coated metal panel coated with a thick coating film showing good capacity can be obtained by applying a primer paint and a topcoat paint to a metal material in combination. The primer coating film is a hard one with Tg of 70-130 deg.C and has a thickness of 5-20 μm. A polyester resin and a blocked polyisocyanate compound are reacted on the primer coating film to be cured to form a topcoating film having Tg of 20-50 deg.C near to the normal temperature and the thickness thereof is 25-60 μm. The coated metal panel satisfying the target properties can be obtained by applying two kinds of the coating films respectively having the Tg ranges to the metal material in a superposed state so as to form a set film thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-layer coated metal sheet coated with a thick film having good hardness, workability, non-adhesion and blocking resistance.

[0002]

2. Description of the Related Art Conventionally, precoated metal sheets coated by continuous coating such as coil coating have been suitably used for exteriors such as roofs, walls, shutters, and garages of buildings. In recent years, in order to extend the life of a structure, further improvement in durability of an exterior coated plate has been demanded.
Therefore, it is necessary to increase the thickness of the coating.

[0003] In the production of precoated metal sheets, baking after coating is characterized by high temperatures and short times. In addition, in order to improve productivity, higher-temperature and shorter-time baking is being pursued. For example, in the case of baking after top coating, conventionally, the maximum temperature of the substrate to be coated and the baking time are 21
0 to 250 ° C. and about 25 seconds, but 210 to 2
It is about to be reduced to 50C and 10-15 seconds.

[0004] In such high-temperature and short-time baking, it has been difficult to form a thick film exceeding 20 µm in a single coating from the viewpoint of resistance to waking.

[0005] Precoated metal sheets require the hardness, workability, non-adhesion and blocking resistance of the coating film. However, if the coating film is made soft to suppress the side effect in thick film coating, the hardness decreases. I will. On the other hand, if an attempt is made to reduce the curing speed of the coating film to suppress the wrinkles, the curing of the coating film becomes insufficient and the non-adhesiveness and blocking resistance of the coating film decrease.
In any case, a large problem occurs in the coating film performance, and it cannot be put to practical use. SUMMARY OF THE INVENTION An object of the present invention is to obtain a multi-layer coated metal sheet which can be coated with a thick film even by baking at high temperature for a short time and has good hardness, workability, non-adhesion and blocking resistance.

The inventors of the present invention have conducted intensive studies to combine the physical properties of the primer coating and the overcoating film, and to obtain a topcoating film formed from a topcoating material having a specific composition.
The inventors have found that the above objects can be achieved, and have completed the present invention.

[0007]

The glass transition point (hereinafter referred to as Tg) of the coated metal sheet of the present invention is at room temperature or slightly higher than room temperature in order to enable thick film coating by baking at high temperature and short time. Use a top coat that becomes a soft coating.

[0008] Such a top coat has a problem that the hardness is low, but a high hardness can be obtained by strongly attaching the coat to a hard surface. Here, the hardness is evaluated by pencil hardness (coating film breakage).

In general, when a top coat is directly applied to a metal surface in the form of a thick film, sufficient adhesion can be obtained due to the difference in the thermal expansion coefficient between the metal and the coat and the generation of shrinkage stress accompanying the curing shrinkage of the top coat. difficult. For this reason, it is difficult to use the effect of improving the hardness of the coating by the hard surface, but by sandwiching a hard primer coating between the top coat and the metal, high adhesion is achieved and the hardness of the top coating is improved. I can do things.

By combining the above findings, a means for achieving the object was found.

Thus, according to the present invention, the pigment (A) contains 80 to 160 parts by weight of the pigment based on 100 parts by weight of the binder, and the glass transition point of the coating film is 70 to 130 ° C.
A primer coating film having a thickness of ２０20 μm is formed, and a binder component (B) is formed from a coating material comprising a hydroxyl group-containing polyester resin and a blocked polysocyanate compound on the primer coating film. 20
The present invention relates to a coated metal sheet characterized by being laminated with a top coat having a temperature of from about 50 ° C. to a thickness of from 25 to 60 μm.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The coated metal plate of the present invention has a primer coating (A) formed on a metal plate, and a top coating (B) formed on the primer coating (A). It is.

In the present invention, the metal plate may or may not be subjected to a chemical conversion treatment. Metal sheets include cold-rolled steel sheets, hot-dip galvanized steel sheets, electrogalvanized steel sheets, and zinc alloys (zinc-iron, zinc-aluminum, zinc-
Alloys such as nickel) plated steel sheet, aluminum plated steel sheet, stainless steel sheet, copper plated steel sheet, tin plated steel sheet,
Metal plate materials such as an aluminum plate and a copper plate, and those obtained by subjecting these metal plate materials to a chemical conversion treatment such as a phosphate treatment or a chromate treatment can be given.

Among them, a galvanized steel sheet (both hot-dip galvanized steel sheet and electrogalvanized steel sheet is included), a zinc alloy-plated steel sheet, the surface of which is subjected to chromate treatment,
Aluminum plated steel plates and aluminum plates are preferred. In particular, a zinc-aluminum-plated steel sheet having a chromate treatment on its surface and having an aluminum content of about 5% by weight in the plating (commonly referred to as "galfan");
It is preferable in terms of corrosion resistance, workability, and the like of the coated metal sheet from which the aluminum-plated steel sheet and the aluminum sheet are obtained.

Primer coating (A) Commercially available coatings can be used for the primer coating used to form the primer coating (A). Above all, a coating material serving as a binder in which at least one organic resin selected from a hydroxyl group-containing polyester resin and an epoxy resin is combined with a curing agent, a primer coating film formed from the primer coating film is a top coating film of the present invention. Is preferred because of its excellent adhesion.

The primer coating of the present invention has a Tg of 70 to
130 ° C., more preferably 80 to 100 ° C.,
It is suitable because the coating film has excellent acid resistance, corrosion resistance, workability, and the like, and can increase the hardness of the overcoat film.

The pigment used in the primer coating of the present invention is not particularly limited, and pigments generally used in coatings can be used.

There is a correlation between the pigment content of the paint and the Tg of the coating film. Generally, as the pigment concentration increases, the Tg of the coating film tends to increase. However, even if the pigment concentration is low, Tg can be increased by using a very hard resin as a binder or by using a large amount of a curing agent to increase the degree of curing of the coating film. Even if the pigment concentration is high, Tg can be reduced by using a very soft resin as a binder or by using a too small amount of a curing agent to suppress the degree of curing of the coating film. However, such Tg adjusting means usually causes various inconveniences. For example, if the pigment concentration is low and the binder is hardened and the degree of curing is increased and the Tg is increased, the stress after curing of the coating film increases, cracks and peeling are likely to occur, and workability and corrosion resistance may be poor. Many. When the pigment concentration is high and the Tg is adjusted by suppressing the softening and curing of the binder, the water resistance and solvent resistance of the coating film are reduced, and the corrosion resistance is also often poor.

From the above, it is possible to obtain good coating performance by determining an appropriate pigment concentration range in order to obtain a coating having a predetermined Tg in consideration of the correlation between the Tg of the coating and the pigment concentration. is important.

The primer paint of the present invention comprises a binder 1
By containing the pigment in an amount of 80 to 160 parts by weight, more preferably 100 to 140 parts by weight, based on 00 parts by weight, it is possible to avoid inconvenience in coating film performance.

The primer coating material of the present invention is applied to a metal plate and baked under a coating method and baking conditions described later to form a cured coating film.

The thickness of the primer coating film (A) of the present invention is 5
２０20 μm. In order to obtain a thick-film coated metal plate, it is preferable that the thickness of the primer coating film is as large as possible.

In the present invention, the Tg of the coating film is Rheog
ta at a frequency of 110 Hz using el-E4000 (a dynamic viscoelasticity measuring device manufactured by UBM Corporation)
The temperature at which tan δ showed a maximum value when the temperature dispersion measurement of n δ was performed.

Topcoat (B) The topcoat (B) of the present invention is a cured coating formed from a topcoat and has a Tg of 20 to 50 ° C. When the Tg is lower than 20 ° C., the hardness of the coating film surface does not become sufficiently high. If the temperature exceeds 50 ° C., the film thickness after curing is 25 μm.
When the above-mentioned thick film is coated and baked and hardened, it is easy to generate a side, and it is difficult to obtain a smooth coated surface.

The top coat comprises, as constituent resin components, a hydroxyl group-containing polyester resin (a) and a blocked polyisocyanate compound (b) as a crosslinking agent.

Hydroxyl-containing polyester resin (a) The hydroxyl-containing polyester resin (a) includes oil-free polyester resins and modified products thereof, for example, urethane-modified polyester resins, epoxy-modified polyester resins, and acryl-modified polyester resins. The hydroxyl group-containing polyester resin (a) preferably has a resin Tg of −25 to + 10 ° C.

The above resin Tg was obtained by differential scanning thermal analysis (DS
C).

The hydroxyl group-containing polyester resin comprises an esterified product of a polybasic acid component and a polyhydric alcohol component. Examples of the polybasic acid component include one or more selected from phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, succinic acid, fumaric acid, adipic acid, sebacic acid, maleic anhydride, and the like. Dibasic acids and lower alkyl esterified products of these acids are mainly used, and if necessary, monobasic acids such as benzoic acid, crotonic acid, pt-butylbenzoic acid, trimellitic anhydride, methylcyclohexenetricarboxylic acid And tribasic or higher polybasic acids such as pyromellitic anhydride. Examples of the polyhydric alcohol component include ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol,
Dihydric alcohols such as neopentyl glycol, 3-methylpentanediol, 1,4-hexanediol and 1,6-hexanediol are mainly used, and if necessary, glycerin, trimethylolethane, trimethylolpropane, pentaerythritol A polyhydric alcohol having a valency of 3 or more can be used in combination. These polyhydric alcohols can be used alone or in combination of two or more. Esterification (including transesterification) of both components can be carried out by a method known per se.

In the present invention, it is preferable to mainly use a combination of isophthalic acid and hexahydrophthalic anhydride as the acid component of the hydroxyl group-containing polyester resin (a) in order to increase the solubility of the resin in an organic solvent. It is preferable that 0.7 or more in mole fraction of the polybasic acid used as a raw material is isophthalic acid and hexahydrophthalic anhydride. The molar ratio of isophthalic acid and hexahydrophthalic anhydride to be blended is preferably from 1/9 to 9/1.

As the polyhydric alcohol of the hydroxyl group-containing polyester resin (a), it is preferable to use 1,6-hexanediol in order to enhance the solvent solubility of the resin. 1,
6-Hexanediol has a large effect of lowering the polarity of the resin and increasing the solubility among the exemplified alcohol raw materials usually used as a polyester raw material. Preferably, the alcohol component of the resin is 1,6-hexanediol in an amount of 10 to 50% by weight of the alcohol component.

When a urethane-modified polyester resin is used as the hydroxyl group-containing polyester resin (a), a resin obtained by reacting an oil-free polyester resin having the above composition with a polyisocyanate compound by a method known per se can be used. As the polyisocyanate compound that can be used at this time, hexamethylene diisocyanate,
Examples include isophorone diisocyanate, xylylene diisocyanate, tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), and 2,4,6-triisocyanatotoluene. As the urethane-modified polyester resin, those having a degree of modification in which the amount of the polyisocyanate compound forming the urethane-modified resin is generally 30% by weight or less based on the urethane-modified resin can be suitably used.

When an epoxy-modified polyester resin is used as the hydroxyl group-containing polyester resin (a), the reaction product between the carboxyl group and the epoxy group-containing resin of the oil-free polyester resin having the above composition, or the hydroxyl group in the polyester resin and the epoxy resin And reaction products such as addition, condensation, and grafting of a polyester resin and an epoxy resin, such as a product in which a hydroxyl group therein is bonded via a polyisocyanate compound. In general, the degree of modification in such an epoxy-modified polyester resin is preferably such that the amount of the epoxy resin is 0.1 to 30% by weight based on the epoxy-modified polyester resin.

When an acrylic modified polyester resin is used as the hydroxyl group-containing polyester resin (a), a group having a reactivity with the carboxyl group or the hydroxyl group of the oil-free polyester resin having the above composition, for example, a carboxyl group, a hydroxyl group or an epoxy group is used. Reaction products with a group-containing acrylic resin and reaction products obtained by graft polymerization of (meth) acrylic acid or (meth) acrylic acid ester with the use of a peroxide-based polymerization initiator can be mentioned. The degree of modification in such an acrylic-modified polyester resin is generally such that the amount of the acrylic resin is 0.1 to
Preferably, it is 50% by weight.

Blocked polyisocyanate compound
(B) Blocked polyisocyanate compound (b) is a compound obtained by blocking free isocyanate groups of a polyisocyanate compound with a blocking agent.

The polyisocyanate compound before blocking is, for example, an aliphatic diisocyanate such as hexamethylene diisocyanate or trimethylhexamethylene diisocyanate; a cyclic aliphatic diisocyanate such as hydrogenated xylylene diisocyanate or isophorone diisocyanate; Or an organic diisocyanate itself such as an aromatic diisocyanate such as 4,4'-diphenylmethane diisocyanate, or an adduct of each of these organic diisocyanates with a polyhydric alcohol, a low molecular weight polyester resin, water, or the like; A cyclized polymer of organic diisocyanates, and an isocyanate / biuret compound may, for example, be mentioned.

Examples of the blocking agent for blocking the polyisocyanate group include phenols such as phenol, cresol and xylenol; ε-caprolactam,
Lactams such as δ-valerolactam and γ-butyrolactam; methanol, ethanol, n-, i- or t-butyl alcohol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, benzyl alcohol Alcohols such as formamidoxime, acetoaldoxime,
Oximes such as acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, and cyclohexane oxime; and active methylenes such as dimethyl malonate, diethyl malonate, ethyl acetoacetate, and acetylacetone can be used. Above all, ε
-It is preferable to use caprolactam. ε-Caprolactam has high solubility of the polyester resin, and has excellent compatibility between the blocked polyisocyanate compound and the polyester resin. Further, ε-caprolactam dissociated during baking easily moves in the coating film and volatilizes, so that it is particularly suitable for thickening and baking at high temperature for a short time.

In the present invention, the top coat (B) is formed by combining the above (a) and (b), and further applying and curing an overcoat containing an organic solvent, a coloring pigment, and the like, if necessary. You. The organic solvent and coloring pigment added here are not particularly limited, and materials generally used for coating materials can be used. Further, if necessary, organic resin powder or inorganic powder; curing catalyst, brilliant pigment;
It may contain additives known per se for coatings, such as lubricity-imparting agents such as polyethylene wax, carnauba wax, and lanolin wax, defoamers, coating surface conditioners, and anti-settling agents.

Method for Producing Painted Metal Sheet In producing the painted metal sheet of the present invention, coating of paint
The curing method is not particularly limited. For example, the coating is performed using roll coating, curtain flow coating, dip coating, spray coating, or the like, and is baked and cured using a far-infrared oven, a hot-air drying oven, or the like.

The curing conditions for both the primer coating and the top coating can be appropriately selected from the baking conditions under which each coating cures. Perform time baking.
When applying primer paint or top coat paint by coil coating that is continuously applied by roll coating etc. on a long metal plate that moves continuously, when baking,
Usually, the maximum temperature of the raw material is 10-1 at 160-260 ° C.
Within the range of 20 seconds, especially the maximum temperature reached 190-250 ° C
And a baking condition of 15 to 90 seconds is suitable.

[0040]

The present invention will now be described more specifically with reference to examples and comparative examples. Hereinafter, "part" and "%"
Are based on weight.

Primer paints The primer paints shown in Table 1 below were used for preparing coated metal plates of Examples and Comparative Examples. All paints are commercially available paints manufactured by Kansai Paint.

[0042]

[Table 1]

Polyester Resin for Top Coating The following Table 2 shows the polyester resins used for producing the top coating.

[0044]

[Table 2]

Using the polyester resin shown in Table 2 above, a paint was prepared with the composition shown in Table 3 below. At this time, the hydroxyl group-containing polyester resin and the blocked polyisocyanate compound were blended such that the hydroxyl groups and the isocyanate groups became equimolar. For the coloring of the paint, the pigments shown in the table were dispersed by an ordinary procedure to obtain a gray paint.

[0046]

[Table 3]

(Note 1) In Table 3, the compounding amount is indicated by solid content weight.

(Note 2) Blocked polyisocyanate compound A: ε-caprolactam blocked polyisocyanate compound, manufactured by Sumitomo Bayer Urethane Co., Ltd., trade name: Desmodur TPLS2957 (Note 3) Blocked polyisocyanate compound B: Sumitomo Bayer Urethane Methyl ethyl ketoxime-blocked polyisocyanate compound, trade name: Desmodur BL3175 (Note 4) Organotin-based curing catalyst, trade name: Takemate Pharmaceutical Co., Ltd., trade name: Formate TK-1 (Note 5) Ishihara Sangyo Rutile-type titanium oxide pigment for paint, manufactured by Co., Ltd., trade name: TAIPEC CR-93 (Note 6) Carbon black black pigment, manufactured by Mitsubishi Kasei Kogyo Co., Ltd., trade name: carbon black MA-100 Example and comparison examples examples following Table 4 and the configuration of the coated plate in the comparative example, gender Table 5 The evaluation results are shown. The contents of the primer paint and the top coat in the table are the same as those in Tables 1 to 3 above.

[0049]

[Table 4]

[0050]

[Table 5]

The procedure for preparing a coated plate in each of the examples and comparative examples is described below.

A 0.5 mm thick zinc-aluminum-plated steel sheet having a surface subjected to a chromate treatment,
The composition of the plating is about 95% by weight of zinc and about 5% by weight of aluminum (the basis weight of plating is 100 g / m ² , which is generally called “galfan”). And baked for 15 seconds so that the maximum temperature of the object to be coated would be 230 ° C. and cured. Further, a top coat was applied on the primer coating so as to have a dry film thickness of 50 μm, and baked for 15 seconds so that the maximum temperature of the object to be coated was 250 ° C. to obtain a coated metal plate.

The coated metal plate thus obtained was evaluated for coating film performance by the following test method.

Test Method Pencil hardness: JIS K-5 for coating film of painted metal plate
400 Pencil scratching test specified in 8.4.2 (1990) was performed, and evaluation by tearing was performed.

Scratch resistance: A 70 μm sapphire needle was attached to a scratch paint hardness tester manufactured by Toyo Seiki Co., Ltd.
A scratch test was performed on the coated surface over a width of 10 cm with a load of 0 g, and the degree of scratches was evaluated according to the following criteria. ：: No exposure of the primer surface was observed. : Slight exposure of the primer surface is observed. : Bare exposure of bare ground. ×: The substrate is significantly exposed.

Workability: In a room at 20 ° C., the coated plate is bent with the coating surface outside, and two spacers having the same thickness as the coated plate are sandwiched inside the coated plate, and the coated plate is placed in a vice for 1 hour.
The state of the coating film at the bent portion when the 2T bending process of bending at 80 degrees was performed was evaluated according to the following criteria. A: No crack was observed on the coating film. : Cracks were slightly observed in the coating film. : Cracks are considerably observed in the coating film. X: Cracks are remarkably observed in the coating film.

Non-adhesion: The coated surface of the coated plate was touched with a finger, and the degree of adhesion of the coated surface was evaluated according to the following criteria. : No stickiness was observed on the coated surface. : A slight stickiness was observed on the coated surface. : Adhesive feeling is considerably recognized on the coated surface. X: Adhesiveness is remarkably recognized on the coated surface.

Blocking resistance: 5 cm × 5 c coated plate
m, and the coated surfaces of the two coated plates were overlapped and left at 50 ° C. under a pressure of 80 kg / cm ² for 24 hours. Thereafter, the ease of peeling of both coated plates was evaluated according to the following criteria. : Both coating plates are not stuck and separated only by tilting. : Both coating plates are slightly stuck, but easily peeled off by hand. : Both coating plates are quite stuck, but can be peeled off by hand without damage to the coating film. ×: Both coated plates are strongly adhered and cannot be peeled off by hand, or even if they can be peeled off by hand, the coating film is damaged.

Adhesion: JIS K5400 8.5.2.
(1990) Using a knife to form 11 crosscuts vertically and horizontally at intervals of about 1 mm using a knife to form a crosscut according to the crosscut tape method. The cross section was extruded by 7 mm from the opposite side of the coating film surface using an Erichsen tester. Thereafter, the coated plate was immersed in boiling water for 6 hours, further immersed in tap water at room temperature for 18 hours, pulled up, and after wiping the surface moisture, tape peeling was performed and evaluated according to the following criteria. ：: There is no peeling of the coating film. : The coating film peeled slightly. ×: The coating film is remarkably peeled.

Waki resistance: Painted surface of painted plate (30 cm × 3
0 cm) was visually observed and evaluated according to the following criteria. : No foam (foaming) was observed on the coated surface. : Slight (foaming) was observed on the coated surface. ×: Remarkable foaming (foaming) is observed on the coated surface.

The weather resistance was evaluated according to the following criteria by measuring the degree of discoloration of the coated surface before and after the test using a sunshine weatherometer for 2,000 hours in accordance with JIS K5400 9.8.1 and measuring the color difference. : Color difference (ΔE according to Hunter's color difference formula) is 2 or less: Color difference exceeds 2 and 5 or less. X: The color difference exceeds 5.

Chemical resistance: The test plate was immersed in a 5% aqueous sodium hydroxide solution maintained at 30 ° C. for 24 hours, pulled up, visually observed on the coated surface, and evaluated according to the following criteria. : No change was observed on the painted surface. : Slight whitening or blistering was observed on the coated surface. X: Whitening or blistering is remarkably observed on the coated surface.

[0063]

The coated metal sheet of the present invention is coated with a multi-layer coating film formed by thick film coating and baking at a high temperature for a short time, and is excellent in hardness, workability, non-adhesion and blocking resistance. ing. The coated metal sheet of the present invention can be suitably used as a precoated metal sheet.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) B05D 7/24 303 B05D 7/24 303Z C08G 18/42 C08G 18/42 Z 18/80 18/80 F-term (Reference) 4D075 AE03 CA02 CA03 CA08 DA06 DB01 DB02 DB04 DB05 DB06 DB07 DC02 DC10 EB33 EB35 EB51 EB53 EB56 EC01 EC02 EC07 EC54 4F100 AB01A AB03 AH03C AK01B AK41C AK51C BA03 BA07 CA13B CC00C JA05BJ01 DC3 DF14 DF16 DF19 DF20 HA01 HA02 HA06 HC03 HC12 HC22 HD04 JA01 QB03 RA07

Claims (5)

[Claims] 1. A primer having a thickness of 5 to 20 .mu.m on a metal plate containing 80 to 160 parts by weight of a pigment based on 100 parts by weight of a binder (A) and having a glass transition point of 70 to 130.degree. A coating film is formed, (B) a binder component is formed from a coating material comprising a hydroxyl group-containing polyester resin and a blocked polysocyanate compound on the primer coating film, and has a glass transition point of 20 to 50 ° C;
A coated metal plate comprising a laminated top coat having a thickness of 25 to 60 μm. 2. The method according to claim 1, wherein the primer coating (A) comprises a binder 10
The coated metal sheet according to claim 1, wherein the pigment is contained in an amount of 100 to 140 parts by weight based on 0 parts by weight, and the glass transition point of the coating film is 80 to 100 ° C. 3. The method according to claim 1, wherein the blocked polyisocyanate compound is ε.
The coated metal sheet according to claim 1 or 2, which is a polyisocyanate compound blocked with caprolactam. 4. The dibasic acid component of the raw material of the hydroxyl group-containing polyester resin is mainly composed of isophthalic acid and hexahydrophthalic anhydride, and the molar ratio of the isophthalic acid to hexahydrophthalic anhydride is from 1/9 to more. 9/1, and the glass transition point of the hydroxyl group-containing polyester resin is -2.
The coated metal sheet according to any one of claims 1 to 3, which is at 5 to 10C. 5. The method according to claim 1, wherein the alcohol component of the hydroxyl group-containing polyester resin contains 10 to 50% by weight of 1,6-hexanediol in the alcohol component. The painted metal sheet according to the item.