JP2003277678A - Thermosetting clear coating material, method for forming multiple layer coating film and coated material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a thermosetting clear coating material forming a second clear coating film without polishing a formed first clear coating film when baking and curing the first coating film in a double clear coating film and capable of obtaining a coating film having high adhesiveness and good appearance, and to provide a method for forming multiple coating film by using the thermosetting clear coating material and to provide a coated material coated by the method. <P>SOLUTION: The thermosetting clear coating material is used for forming the first clear coating film of the multiple coating film successively having a base coating film, the first clear coating film and the second clear coating film on a substrate to be coated. The thermosetting clear coating material contains an acrylic resin, a polyester oligomer, an iminomethylol type methylated melamine resin and an iminomethylol type butylated melamine resin. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosetting clear coating material for forming a high-appearance coating film, a method for forming a multilayer coating film using this thermosetting clear coating material, and a coated article coated by this method.

[0002]

2. Description of the Related Art An automobile body is first coated with an electrodeposition paint and baked, and then an intermediate coating film is formed thereon, and an overcoat comprising a base coating film and a clear coating film is further applied. .

The clear coating film is formed in order to protect the base coating film as the lower layer and to enhance the appearance of the substrate to be coated, but it is generally carried out wet on wet. Further, it is known to form two or more clear coating films when a higher appearance is obtained or when the particle size of the pigment in the base coating film is large. These methods are described in, for example, Japanese Patent Laid-Open No.
No. 1-253877. They are,
It is called a double clear coating film. When the first clear coating film is baked and cured to form the second clear coating film, the first clear coating film formed to secure adhesion and appearance of the coating film is polished. is doing.

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a second clear coating without polishing the first clear coating formed when the first clear coating in the double clear coating is baked and cured. To provide a thermosetting clear coating that forms a film to obtain a high adhesion and high appearance coating film, a method for forming a multilayer coating film using this thermosetting clear coating, and a coated article coated by this method. is there.

[0005]

Means for Solving the Problems The present inventors have accomplished the present invention as a result of intensive studies in view of the above problems. 1. In a thermosetting clear coating material used for forming a first clear coating film of a multilayer coating film having a base coating film, a first clear coating film, and a second clear coating film in sequence on a substrate to be coated, a vehicle As the above, a thermosetting clear coating material containing an acrylic resin, a polyester oligomer, an iminomethylol-type methylated melamine resin and an iminomethylol-type butylated melamine resin. 2. The thermosetting clear coating composition, wherein the acrylic resin has a hydroxyl value of 50 to 200, an acid value of 2 to 30, a number average molecular weight of 5,000 to 10,000, and a solubility parameter of 10.5-11.5. 3. The hydroxyl value of the polyester oligomer is 50 to 2
50, acid value 2 to 30, number average molecular weight 1000 to 30
00, the thermosetting clear coating composition having a solubility parameter of 10.5-11.5. 4. The thermosetting clear coating material, wherein the acrylic resin / polyester oligomer solid content ratio is 95/5 to 30/70. 5. The thermosetting clear coating composition, wherein the solid content ratio of the iminomethylol type methylated melamine resin / iminomethylol type butylated melamine resin is 80/20 to 20/80. 6. The acrylic resin and the polyester oligomer /
The thermosetting clear coating composition, wherein the solid content ratio of the iminomethylol type methylated melamine resin and the iminomethylol type butylated melamine resin is 80/20 to 40/60. 7. A step of applying a base paint on a substrate to be coated to form a base paint film; a step of applying the thermosetting clear paint thereon to form a first clear paint film; the first clear paint film A method for forming a multilayer coating film, which comprises the steps of baking and curing the composition; a step of applying a clear coating composition thereon to form a second clear coating film; and a step of curing the second clear coating film. 8. The clear coating material used for forming the second clear coating film is a thermosetting clear coating material containing, as a vehicle, a carboxyl group-containing polymer and an epoxy group-containing polymer, and the multilayer coating is carried out by baking. Film forming method. 9. A coated article coated by the above method for forming a multilayer coating film.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The constitution of the present invention will be described in detail below. In addition, the compounding amount, compounding ratio, and addition amount in the present specification are amounts in terms of solid content, unless otherwise specified.

[Thermosetting Clear Coating Material] The thermosetting clear coating material of the present invention is a multilayer coating film formation in which a base coating film, a first clear coating film, and then a second clear coating film are sequentially formed on a substrate to be coated. In the method, the paint used for forming the first clear coating film, wherein the vehicle used for the paint contains an acrylic resin, a polyester oligomer, an iminomethylol-type methylated melamine resin, and an iminomethylol-type butylated melamine resin. Is.

The acrylic resin used for the thermosetting clear coating composition can be obtained by copolymerizing an acrylic monomer and another ethylenically unsaturated monomer. Acrylic monomers that can be used in the above copolymerization include methyl, ethyl, propyl, and n- of acrylic acid or methacrylic acid.
Ring-opening addition of caprolactone of butyl, i-butyl, t-butyl, 2-ethylhexyl, lauryl, phenyl, benzyl, 2-hydroxyethyl, 2-hydroxypropyl and other ester compounds, acrylic acid or 2-hydroxyethyl methacrylate. Substances, glycidyl acrylic acid or methacrylate, acrylamide, methacrylamide and N-methylol acrylamide, mono (meth) acrylic acid ester of polyhydric alcohol, and the like. on the other hand,
Other ethylenically unsaturated monomers copolymerizable with these include styrene, α-methylstyrene, itaconic acid, maleic acid, vinyl acetate and the like.

The acrylic resin has a hydroxyl value of 50 to 2
00, acid value 2 to 30, number average molecular weight 5000 to 10
000, and the solubility parameter is preferably 10.5-11.5.

If the hydroxyl value is less than 50, the adhesion with the second clear coating film may be insufficient, and if it exceeds 200, the appearance of the coating film, especially the skin of the coating film may be deteriorated and the adhesion to the base coating film may be deteriorated. Familiarity may occur and the finished multilayer coating film may have a blurred feeling, and is more preferably 75 to 150. If the acid value is less than 2, curing may be insufficient,
If it exceeds 30, the storage stability of the coating composition may decrease, and it is more preferably from 5 to 20. When the number average molecular weight is out of the above range, the coating film performance and appearance may be insufficient, and more preferably 6000 to 9000. If the solubility parameter is less than 10.5, the wettability of the second clear coating film may be deteriorated and the coating appearance may be deteriorated, or the adhesion to the second clear coating film may be decreased.
If it exceeds the range, there is a risk that the base coating film may become familiar with the finished coating film and the finished multilayer coating film may have a blurring feeling, and more preferably 10.8 to 11.3.

As the polyester oligomer used in the thermosetting clear paint, a resin which is a condensation product of a polyhydric alcohol and a polycarboxylic acid is used.

Suitable polyhydric alcohols for producing the above polyester oligomer are ethylene glycol, propylene glycol, butylene glycol, 1,6-hexylene glycol, neopentyl glycol, glycerol,
It includes trimethylolpropane, trimethylolethane, pentaerythritol, dipentaerythritol, tripentaerythritol, hexanetriol, and condensation products of trimethylolpropane with ethylene oxide or propylene oxide.

Suitable polycarboxylic acids include succinic acid (or its anhydride), adipic acid, azelaic acid, sebacic acid, maleic acid, (or its anhydride), fumaric acid, muconic acid, itaconic acid, phthalic acid (or Its anhydride),
Includes isophthalic acid, terephthalic acid, trimellitic acid (or its anhydride) and pyromellitic acid (or its anhydride).

The thermosetting clear coating material of the present invention is obtained by preparing the synthesis and adjusting the number average molecular weight.

The above polyester oligomer has a hydroxyl value of 50 to 250, an acid value of 2 to 30, and a number average molecular weight of 10.
00-3000, solubility parameter 10.5-11.
It is preferably 5.

If the hydroxyl value is less than 50, the curability may be inferior and the adhesion to the second clear coating film may be insufficient, and if it exceeds 250, the finished multilayer coating film may be blurred. Yes, and more preferably 75 to 200. If the acid value is less than 2, curing may be insufficient, and if it exceeds 30, the storage stability of the coating composition may be reduced, and more preferably 5 to 20. When the number average molecular weight is out of the above range, the coating film performance and appearance may be insufficient, and more preferably 1200 to 2000. If the solubility parameter is less than 10.5, the wettability of the second clear coating film may be deteriorated and the adhesion of the second clear coating film may be deteriorated. If it exceeds the range, there is a risk that the base coating film may become uncomfortable and the finished multilayer coating film may have a blurring feeling, and more preferably 1
It is 0.8-11.3.

Further, the solid content ratio of the acrylic resin / the polyester oligomer is 95/5 to 30/7.
It is preferably 0.

If this ratio is less than 30/70, the hardness and wettability may be lowered, and if it exceeds 95/5, the appearance of the coating film, particularly the coating surface may be deteriorated. More preferably, it is 80/20 to 50/50.

Also used as a cross-linking agent for the vehicle of the thermosetting clear paint is an imino group type melamine resin mixture with an iminomethylol type methylated melamine resin and an iminomethylol type butylated melamine resin.

The solid content ratio of the iminomethylol type methylated melamine resin / iminomethylol type butylated melamine resin is preferably 80/20 to 20/80. If the solid content ratio of the iminomethylol type methylated melamine resin / iminomethylol type butylated melamine resin exceeds 80/20, the sagging property at the time of forming a coating film may decrease, and if it is less than 20/80, a coating film is formed. There is a risk of deterioration of the appearance, especially the surface of the coating film. More preferably, 70/3
It is 0 to 30/70.

In the above-mentioned thermosetting clear paint, by using the acrylic resin, the polyester oligomer and the specific melamine resin as vehicles,
The surface tension of the first clear coating film can be increased, and when the second clear layer is coated on the first clear coating film, the wettability is improved and the adhesion between both coating films is improved. Even if the clear coating film is baked and cured, it is not necessary to polish the first clear coating film surface.

The ratio of the acrylic resin + the polyester oligomer and the imino group-type melamine resin mixture is 80 to 50% by weight of the acrylic resin + the polyester oligomer in terms of solid content, and the imino group-type melamine resin mixture is 20%. % To 50% by weight, preferably 75 to 50% by weight of the acrylic resin + the polyester oligomer.
55% by weight, and the imino group-type melamine resin mixture is 25 to 45% by weight. When the imino group-type melamine resin mixture is less than 20% by weight (when the acrylic resin + the polyester oligomer exceeds 80% by weight),
The curability of the first clear coating film may decrease. On the other hand, when the imino group-type melamine resin mixture exceeds 50% by weight (when the acrylic resin + the polyester oligomer is less than 50% by weight), the curing reaction of the first clear coating film proceeds too much, resulting in the second clear coating film. There is a risk that the adhesiveness with

In the first clear coating composition, a coloring pigment or an extender pigment can be used within a range that does not impair the transparency. As the color pigment, as an organic pigment, an azo lake pigment, an insoluble azo pigment, a condensed azo pigment,
Phthalocyanine pigment, indigo pigment, perinone pigment, perylene pigment, phthalone pigment, dioxazine pigment, quinacridone pigment, isoindolinone pigment,
Examples thereof include metal complex pigments, and examples of the inorganic type include yellow iron oxide, red iron oxide, carbon black, titanium dioxide and the like. Further, talc as the extender pigment,
Examples thereof include calcium carbonate, precipitated barium sulfate, silica and the like.

In the first clear coating composition, an ultraviolet absorber, a hindered amine light stabilizer, an antioxidant as an additive, a crosslinked resin particle as a rheology control agent,
Silicone or acrylic surface conditioners can be added.

The method for producing the first clear paint is not particularly limited, and any method known to those skilled in the art can be used. The solid content of the first clear coating material is preferably in the range of 30 to 80% by weight at the time of production and 20 to 70% by weight at the time of coating.

[Method for forming multi-layer coating film] The method for forming a multi-layer coating film of the present invention comprises a base coating film, a first clear coating film,
Then, a second clear coating film is sequentially formed, and before forming the second clear coating film, the first clear coating film formed by the thermosetting clear coating composition is baked and cured to form a multilayer coating film. Is.

The above-mentioned base material to be coated is not limited, and metals such as iron, aluminum, copper or alloys thereof; polyethylene resin, polypropylene resin, ethylene-vinyl acetate copolymer resin, polyamide resin, Acrylic resin, vinylidene chloride resin, polycarbonate resin,
Resins such as polyurethane resin and epoxy resin and various F
An example is a plastic material such as RP that has been subjected to a conductive treatment. Examples of the base material to be coated include vehicles such as automobiles, furniture,
Examples include home electric appliances.

In the case of a coating film forming process in an automobile body to which the present invention is preferably used, first, a base material to be coated is subjected to degreasing and chemical conversion treatment before forming a coating film. Next, an electrodeposition coating film is formed by electrodeposition coating, and an intermediate coating film is further formed. It is preferable that these coating films are baked and cured. In the present specification, a substrate on which these coating films are formed is also a substrate to be coated.

The electrodeposition paint used for forming the above-mentioned electrodeposition coating film uses a commonly used anion type and cation type epoxy resin or acrylic resin and a cross-linking agent such as block polyisocyanate compound or melamine resin as a vehicle. It is a paint in which a pigment and other materials are appropriately mixed.

The intermediate coating composition used for forming the intermediate coating film is a polyester resin obtained from a polyhydric alcohol and a polybasic acid, an alkyd resin modified with an oil or the like, or an acrylic monomer is radical-polymerized. This is a coating composition in which the acrylic resin obtained by the above and a crosslinking agent such as a melamine resin or a blocked polyisocyanate compound are used as a vehicle, and a rust preventive pigment, a chipping-resistant pigment, and other materials are appropriately mixed therein. In the multilayer coating film forming method according to the present invention,
A base coating film is formed on the entire substrate to be coated. The base coating film can be a glittering base coating film or a solid base coating film.

As the glittering base paint or solid base paint used for forming the glittering base coating film or solid base coating film, a polyester resin, an alkyd resin, an acrylic resin and a crosslinking agent such as a melamine resin or a block polyisocyanate are used. Is a vehicle, and an aluminum foil, a bright pigment such as a mica pigment, or a coloring pigment described below is appropriately mixed with the vehicle.

The base coating film is formed by applying the glittering base coating material or the solid base coating material on the surface of the substrate to be coated so as to have a dry film thickness of 3 to 25 μm. The formed coating film may be heat-cured at this stage, but it is usually preferable to bake it after forming the first clear coating film by the above-mentioned thermosetting clear coating on wet-on-wet. . The glitter base paint or solid base paint may be an organic solvent type paint using an organic solvent as a solvent, or water or an aqueous paint using a hydrophilic organic solvent as the case requires.

In the method for forming a multilayer coating film of the present invention, next,
On the base coating film thus formed, the thermosetting clear coating material is formed as a first clear coating film.
Here, the dry film thickness of the first clear coating film is 20 to 1
It is preferably 00 μm. The first clear coating film is baked and cured, and then the second clear coating film is formed on the entire substrate to be coated. The baking of the first clear coating film is preferably carried out at a temperature of 100 to 180 ° C., more preferably 120 to 160 ° C. for 10 to 30 minutes. By setting the conditions in this way, a cured coating film having a high degree of crosslinking can be obtained.

In the method for forming a multilayer coating film of the present invention, next,
A second clear coating film is formed on the entire surface of the coated substrate.

Second used for forming the second clear coating film
The clear paint may use the same acrylic resin and melamine resin as those used in the first clear paint, or a crosslinking agent such as a blocked polyisocyanate compound as a vehicle. Also, from the viewpoint of acid resistance of the obtained multilayer coating film,
The second clear paint is preferably a thermosetting clear paint containing a carboxyl group-containing polymer and an epoxy group-containing polymer. These are Japanese Examinations 8-19
No. 315 publication. More preferably,
(A) A copolymer of a radically polymerizable monomer having an acid anhydride group and another copolymerizable monomer, wherein the acid anhydride group in the copolymer is half-esterified, 30 to 70% by mass of a radical-polymerizable monomer (B) (b1) having an epoxy group,
(B2) 10 to 10 radically polymerizable monomer having a hydroxyl group
Epoxy equivalent of 100 to 800 and hydroxy equivalent of 200 to 50 obtained by copolymerizing a monomer composition containing 50% by mass and (b3) other radically polymerizable monomer as the remaining amount.
It is a thermosetting clear coating composition using a copolymer of 1200 and a molecular weight of 1000 to 8000 as a vehicle.

In the above curable resin, the total number of epoxy groups of the compound (B) / the total number of half-esterified acid anhydride groups of the copolymer (A) = 0.5 to 1.5, particularly 0.6 to
1.2 is preferable, and the total number of hydroxyl groups of the compound (B) / the total number of half-esterified acid anhydride groups of the copolymer (A) = 0.1 to 1.5, particularly 0.3 to 1 It is preferably 0.2. The compounding amount of the compound (B) that gives the above ratio is, for example, 50 to 100 parts by mass of the copolymer (A).
It is preferably 250 parts by mass, particularly preferably 80 to 150 parts by mass. If the amount of the compound (B) used is less than 50 parts by mass, sufficient curing may not be performed, and the water resistance, weather resistance, etc. of the cured coating film may decrease. On the other hand, if it exceeds 250 parts by mass, unreacted carboxyl groups may remain and the chemical resistance may decrease.

Since the thermosetting resin has an acid group as a functional group, it can be neutralized with an amine to give an aqueous resin composition containing water as a medium.

The second clear paint may contain a coloring pigment, an extender pigment, and an additive as in the first clear paint. The contents described in the description of the first clear paint are applied to these as they are. Further, regarding the manufacturing method and the solid content, the contents described in the explanation of the first clear paint are applied as they are. The dry film thickness of the second clear coating film is preferably 20 to 100 μm. If the dry film thickness of the second clear coating film is less than 20 μm, it may not be possible to form a coating film having a high appearance.
If it exceeds μm, there may be a problem in the physical properties of the coating film.

The baking of the second clear coating film thus formed is preferably 100 to 180 ° C., more preferably 120 to 160 ° C., like the first clear coating film.
For 10 to 30 minutes. Thus, a multilayer coating film using the double clear coating film can be obtained.

[Coated Product] The coated product of the present invention is obtained by the above method for forming a multilayer coating film. The coated article of the present invention is one in which a base coating film, a first clear coating film formed by a thermosetting clear coating composition having the above specific composition, and then a second clear coating film are sequentially formed on a substrate to be coated, Even when the first clear coating film is baked and cured, a high-adhesion and high-appearance multilayer coating film capable of forming a second clear coating film without polishing the formed first clear coating film is formed. ing.

[0041]

EXAMPLES Next, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. In addition, the compounding amount represents a mass part unless otherwise specified.

Examples 1 to 9 and Comparative Examples 1 to 5 [Preparation of substrate for coating] After degreasing a dull steel plate (thickness 0.8 mm), a zinc phosphate treatment agent (“Surfdyne SD2000”,
After chemical conversion treatment using Nippon Paint Co., Ltd., the entire steel sheet was electrodeposition coated with a cationic electrodeposition paint (“Power Top U-50”, Nippon Paint Co., Ltd.) so that the dry film thickness was 25 μm. Then, after baking at 160 ° C. for 30 minutes, an intermediate coating (“Olga S-90 Sealer Gray”,
An air spray coating (Nippon Paint Co., Ltd.) was applied so that the dry film thickness was 40 μm, and baking was performed at 140 ° C. for 30 minutes to form an intermediate coating film, which was used as a substrate to be coated.

[Preparation of first clear coating] Acrylic resin having hydroxyl value / acid value / number average molecular weight and solubility parameter shown in Table 1, polyester oligomer having hydroxyl value / acid value / number average molecular weight and solubility parameter , An iminomethylol-type methylated melamine resin and an iminomethylol-type butylated melamine resin in a ratio shown in Table 1 for forming a first clear coating film.
~ 11 were prepared.

[0044]

[Table 1]

[Formation of multi-layer coating film] A base coating film having a dry film thickness of 15 μm was formed on the entire substrate to be coated with the base coating material. After forming a first clear coating film on it by wet-on-wet with the thermosetting clear coating material shown in Table 1, 1
Bake at 40 ° C for 30 minutes, and further on the entire substrate to be coated,
A second clear coating film having a dry film thickness of 35 μm was formed from the second clear coating material. This was baked at 140 ° C. for 30 minutes to obtain a multilayer coating film. The adhesion between the first clear coating film and the second clear coating film and the appearance of the coating film were evaluated, and the results are shown in Table 2.

[Base paint and second clear paint] Base paint 1: Organic solvent type acrylic / melamine resin topcoat glittering paint ("Superlac M-300", manufactured by Nippon Paint Co., Ltd.) Base paint 2: Organic solvent type acrylic / Melamine resin-based top coating color coating ("Superlac M-90", manufactured by Nippon Paint Co., Ltd.) Base coating 3: Water-based acrylic / melamine resin-based top coating glitter coating ("Supernix M280", manufactured by Nippon Paint Co., Ltd.) 2nd clear Paint A: Clear paint containing carboxyl group-containing polymer and epoxy group-containing polymer (“Macflow O-590 Clear”, manufactured by Nippon Paint Co., Ltd.) Second clear paint B: Acrylic / melamine resin-based clear paint (“Superlac”) O-80 clear "manufactured by Nippon Paint Co., Ltd.)

[Evaluation method] Appearance of coating film: The appearance of the coating film after formation of the multilayer coating film was visually evaluated for the appearance of sharpness.

[0048]

[Table 2]

Adhesion: The test piece after forming the multi-layer coating was peeled off by 100 tapes of 1 mm crossing reaching the coating film base by a tape test according to JIS K 5400 using a cellophane adhesive tape. The number of crosses was measured.

[0050]

[Table 3]

[0051]

[Table 4]

As is clear from the results shown in Table 4, this Example is a coated article obtained by the method for forming a multilayer coating film of the present invention, and the first clear coating film is baked and cured. Even without polishing the first clear coating film, good adhesion and a high-finished appearance coating film were obtained. On the other hand, in the comparative example, at least one of the adhesiveness and the appearance of the coating film was not sufficient.

[0053]

According to the present invention, when a double clear coating film is formed, the first clear coating film and the second clear coating film can be formed without polishing the first clear coating film formed on the horizontal portion. Adhesion is good, and in addition, a high-quality finished appearance of a multilayer coating film can be obtained.

The coated article obtained according to the present invention comprises a base coating film, a first clear coating film formed of a thermosetting clear coating composition having the above-mentioned specific composition, and then a second clear coating film formed on the substrate. Since the curing reaction was stable, the formed multilayer coating film had good coating appearance and good adhesion to the top coating film.

Since the coated product obtained by the present invention has the above-mentioned good adhesion and coating film appearance, it is preferably used in fields such as vehicle outer plates of automobiles and motorcycles, outer surfaces of containers, coil coating, the home appliance industry and the like. .

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C09D 163/00 C09D 163/00 167/00 167/00 201/08 201/08 (72) Inventor Masuo Kida 4-1-115 Minami-Shinagawa, Shinagawa-ku, Tokyo Within Japan Paint Co., Ltd. (72) Inventor, Hakshu Tanaka 4-1-1-15 Minami-Shinagawa, Shinagawa-ku, Tokyo Japan Paint Co., Ltd. F-term (reference) BB26Z CB06 DA06 DA23 DB01 DB02 DB06 DB07 DB36 DB38 DB40 DB43 DB47 DB48 DB50 DB53 DB61 DB63 DC12 DC18 DC38 EA19 EA43 EB22 EB32. GB32 JA07B JA09B JA20B JK14 JK15 JL11 YY00B 4J038 CG001 CG002 CG141 CG142 CG171 CG172 CH031 CH032 CH041 CH042 CH121 CH122 CH161 CH162 CH171 CH172 DA161 DA162 DD001 DD002 DD041 DD042 GA03 GA06 GA07 KA08 MA14 PA19 PB03 PC02

Claims (9)

[Claims] 1. A thermosetting material used for forming a first clear coating film of a multilayer coating film, which comprises a base coating film, a first clear coating film, and a second clear coating film on a substrate to be coated in order. In the clear coating, a thermosetting clear coating containing as a vehicle an acrylic resin, a polyester oligomer, an iminomethylol-type methylated melamine resin and an iminomethylol-type butylated melamine resin. 2. The hydroxyl value of the acrylic resin is 50 to 2
00, acid value 2 to 30, number average molecular weight 5000 to 10
000 and the solubility parameter is 10.5-11.5, The thermosetting clear paint according to claim 1. 3. The polyester oligomer has a hydroxyl value of 50 to 250, an acid value of 2 to 30, and a number average molecular weight of 10.
00-3000, solubility parameter 10.5-11.
5. The thermosetting clear coating composition according to claim 1, which is 5. 4. The thermosetting clear coating material according to claim 1, wherein a solid content ratio of the acrylic resin / the polyester oligomer is 95/5 to 30/70. 5. The thermosetting resin composition according to claim 1, wherein a solid content ratio of the iminomethylol-type methylated melamine resin / the iminomethylol-type butylated melamine resin is 80/20 to 20/80. Sex clear paint. 6. The solid content ratio of the acrylic resin, the polyester oligomer / the iminomethylol type methylated melamine resin and the iminomethylol type butylated melamine resin is 80/20 to 40/60.
5. The thermosetting clear coating composition according to any one of 5 to 5. 7. A step of applying a base coating material on a substrate to be coated to form a base coating film; applying the thermosetting clear coating material according to claim 1 thereon. A step of forming a clear coating film; a step of baking and curing the first clear coating film; a step of applying a clear coating material thereon to form a second clear coating film; and curing the second clear coating film A method for forming a multilayer coating film, including the step of :. 8. The clear coating material used for forming the second clear coating film is a thermosetting clear coating material containing, as a vehicle, a carboxyl group-containing polymer and an epoxy group-containing polymer, and the curing is performed by baking. The method for forming a multilayer coating film according to claim 7. 9. A coated article coated by the method for forming a multilayer coating film according to claim 7 or 8.