JPH0762269A - Powder coating composition giving honeycomb pattern, its coating method, coating film and coated product - Google Patents

Abstract

PURPOSE:To obtain a powder coating composition giving a uniform and dense honeycomb pattern having excellent steric designability and excellent coating film performance by compounding a specific curing agent and a specific curing catalyst to a powder coating resin having specific hydroxyl value and exhibiting solid state at normal temperature. CONSTITUTION:This powder coating composition is produced by mixing (A) 60-95 pts.wt. of a powder coating resin having a hydroxyl value of 10-320mgKOH /g and exhibiting solid state at normal temperature (e.g. acrylic resin) with (B) 5-40 pts.wt. of a toluenesulfonamide-modified melamine resin having a glass- transition temperature of 30-70 deg.C as a curing agent and compounding 100 pts.wt. of the obtained mixture with (C) 0.1-3 pts.wt. (in terms of sulfonic acid) of a curing catalyst consisting of a sulfonic acid compound having a boiling point of 80-250 deg.C and blocked with an amine compound having secondary or tertiary amino group (e.g. p-toluenesulfonic acid blocked with tripropylamine). The component C is preferably produced by charging a reactor with the above amine compound and the sulfonic acid compound and stirring at 20-30 deg.C for 10-20min.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder coating composition for imparting a hexagonal pattern on the surface of a coating film, a coating method therefor, a coating film and a coated product.

[0002]

2. Description of the Related Art Powder coatings have been spreading to fields of use due to advantages such as pollution-free and labor saving, but in recent years, development of powder coatings having a design property on the coating film surface has been strongly demanded. As a method for imparting a design property to the coating film surface of a powder coating, for example, JP-A-60-168771 discloses a method of mixing a polyester resin-based powder coating composition and an acrylic resin-based powder coating composition. A powder coating composition for a precoat which gives a coating film having an uneven pattern is disclosed.

In Japanese Patent Laid-Open No. 63-91168, two types of powder coatings containing a powdery silicon-based additive in one or both of them are used, and two coats and one bake are used to produce a hammer tone, a pearl tone, etc. Discloses a method for forming a special pattern coating film by the powder coating. Further, Japanese Patent Application Laid-Open No. 1-288376 discloses a method for producing a coated metal plate having an uneven pattern in which a thermoplastic resin is mixed with a thermosetting powder coating material to obtain an uneven pattern.

However, in any coating composition,
Although it is possible to form a simple uneven pattern, it was not possible to form a uniform and dense coating film having a hexagonal pattern having excellent designability.

[0005]

An object of the present invention is to provide a hexagonal pattern which is uniform and dense and has a three-dimensional appearance and excellent design characteristics, which is different from the conventional concavo-convex pattern, and is also excellent in coating film performance. And a powder coating composition.

Another object of the present invention is a coating method of the above powder coating composition, which is excellent in coating film performance, and is uniform and dense and has a three-dimensional effect, which is different from the conventional uneven pattern. It is to propose a simple coating method for forming a turtle shell pattern having a design property.

Another object of the present invention is a coating film formed from the above powder coating composition, which is excellent in coating film performance and has a uniform and dense three-dimensional appearance, which is different from the conventional uneven pattern. It is an object of the present invention to provide a turtle shell pattern coating film having a certain excellent design property.

Still another object of the present invention is a coated article having a coating film formed from the above powder coating composition, which has excellent coating film performance and is uniform and dense unlike conventional uneven patterns. Thus, it is an object of the present invention to provide a coated article having a tortoiseshell pattern having a three-dimensional effect and excellent designability.

[0009]

The present invention is the following powder coating composition, its coating method, coating film and coated article. (1) (A) 60 to 95 parts by weight of a resin for powder coating which has a hydroxyl value of 10 to 320 mgKOH / g and is solid at room temperature,
(B) To 100 parts by weight of a mixture consisting of 5 to 40 parts by weight of a toluenesulfonamide-modified melamine resin having a glass transition temperature of 30 to 70 ° C., (C) a secondary or tertiary amino group having a boiling point of 80 to 250 ° C. A sulfonic acid compound blocked with an amine compound having
A powder coating composition giving a hexagonal pattern, characterized in that it is contained in an amount by weight. (2) After coating the powder coating composition according to (1) above on a substrate, baking at a temperature of 150 to 300 ° C. for 20 seconds to 60 minutes to form a coating film having a thickness of 20 to 200 μm. A method for coating the powder coating composition according to the above (1), characterized in that (3) The powder coating composition according to the above (1) is applied onto a substrate and then baked at a temperature of 150 to 300 ° C. for 20 seconds to 60 minutes to have a thickness of 20 to 200 μm. A coating film formed from the powder coating composition according to (1) above. (4) A coating film having a thickness of 20 to 200 μm, which is formed by applying the powder coating composition according to (1) above on a substrate and then baking at a temperature of 150 to 300 ° C. for 20 seconds to 60 minutes. A coated article having a coating film formed from the powder coating composition according to (1) above.

The resin for powder coating composition containing a hydroxyl group of the component (A) used in the present invention, which is solid at room temperature, is a solid resin at room temperature which is used for powder coating and has a hydroxyl value of 10 to 32.
0 mgKOH / g, preferably 25-300 mgKOH
/ G, glass transition temperature (Tg) is 30 to 120 ° C., preferably 35 to 100 ° C. Examples of the component (A) include a hydroxyl group-containing acrylic resin, polyester resin, fluororesin, and the like, and any of the commercially available products and synthetic products can be used.

As the acrylic resin for powder coating, for example, Almatex PD-800 manufactured by Mitsui Toatsu Chemicals, Inc.
0, the same PD-8100, S.I. C. JONCRYL J-587, J-800 and SCX manufactured by Johnson.
-802 (both are trade names).

Examples of the polyester resin for powder coating include ER-6620 and ER-6 manufactured by Nippon Ester Co., Ltd.
640, XI-6021, XI-70009, XI-70
19, Dainippon Ink & Chemicals Co., Ltd. FA Index M-8000, M-8070, M-8076, Nippon Yupica Co., Ltd. Yupica Coat GV-110, GV.
-150, the same GV-741, P manufactured by Hitachi Chemical Co., Ltd.
C resin 2H, 3H, DSM URALAC P
-4215, CARGILL 30-3000, 3
0-3002, 30-3011, 30-3012, 30
-3020, Crylcot 2383, 2392, and 3145, manufactured by UCB, and Crelan, manufactured by Bayer.
U-502, Hoechst Alftalat
AN-739, AN-759, VAN9969
(Both are trade names).

Examples of the fluororesin for powder coating include Lumiflon LF-710 (trade name) manufactured by Asahi Glass Co., Ltd. These components (A) can be used alone or in combination of two or more.

The toluenesulfonamide-modified melamine resin as the component (B) used in the present invention is a condensate of melamine-formaldehyde condensate ether (MF) and toluenesulfonamide (TS) and has a glass transition temperature (Tg).
Is 30 to 70 ° C., preferably 35 to 50 ° C.

The above-mentioned toluenesulfonamide-modified melamine resin contains a non-crosslinked condensate oligomer obtained by condensing 1 mol of MF and 1 to 4 mol of TS, and this condensate oligomer is -CH ₂ -or -CH _2. OCH ₂ - include crosslinked oligomer crosslinked by group. The toluenesulfonamide-modified melamine resin composed of such an oligomer mixture has a number average molecular weight (Mn) of 600 to 2000, preferably 700 to 1600, and a molecular weight distribution (Mw / Mn).
Is 1 to 7, preferably 2 to 6, functional group equivalent to RO-130 to 200 g / equivalent, preferably 150 to 18
A suitable amount is 0 g / equivalent, and the amount of functional groups contained in one molecule of the oligomer is 4 to 10, preferably 5 to 8.

The basic reaction formula for producing a toluenesulfonamide-modified melamine resin (TS-MF) from MF and TS is shown in formula [1].

[0017]

[Chemical 1] (In the formula, R represents an alkyl group, at least three of the six are methyl groups, and the rest are alkyl groups having 2 to 4 carbon atoms.)

As the toluenesulfonamide-modified melamine resin, one using hexamethoxymethylmelamine for MF is preferable, and Progress Organic Coating, 20 is particularly preferable.
(1992) pp301 to 323, resins M-1 and M-2,
M-3 is preferred.

The boiling point of the component (C) used in the present invention is 80 to 2
A sulfonic acid compound blocked with an amine compound having a secondary or tertiary amino group at 50 ° C. (hereinafter sometimes referred to as a blocked acid catalyst) is used as a curing catalyst, and includes, for example, paratoluenesulfonic acid and dodecyl. Aromatic sulfonic acids such as benzene sulfonic acid, dinonylnaphthalene sulfonic acid, dinonyl naphthalene disulfonic acid, and the following structural formulas [2] to

One or two or more kinds of the aliphatic sulfonic acid and the like represented by [9] are added with a boiling point of 80 to 25.
It is blocked with an amine compound having a secondary or tertiary amino group at 0 ° C.

[0020]

[Chemical 2] (In the formula, R ¹ represents an alkyl group having 1 to 22 carbon atoms, R ² represents an alkyl group having 4 to 8 carbon atoms, and R ³ represents an alkyl group having 13 to 17 carbon atoms.)

Use of an aliphatic sulfonic acid is preferable because it has better compatibility with a resin than an aromatic sulfonic acid, and thus there is little risk of crystallization in a coating material and causing a spot on the coating film. Aliphatic sulfonic acid is obtained by converting sodium sulfonate or potassium sulfonate, which is generally used as a surfactant, such as sodium salt or potassium salt into sodium hydroxide or potassium salt to convert it into a free acid. You can

Here, examples of the aliphatic sulfonate as the starting material include those represented by the following structural formulas [10] to [17].

[0023]

[Chemical 3] (In the formula, R ⁴ represents an alkyl group having 1 to 22 carbon atoms, R ⁵ represents an alkyl group having 4 to 8 carbon atoms, and R ⁶ represents an alkyl group having 13 to 17 carbon atoms.)

These aliphatic sulfonates can be converted into free acids by sodium removal or potassium removal with an inorganic acid. An aliphatic sulfonate having less than 4 carbon atoms has a difficulty in compatibility with a resin as in the case of an aromatic sulfonic acid, and therefore, one having 4 or more carbon atoms is preferable.

As the above-mentioned inorganic acid, ordinary sulfuric acid, hydrochloric acid,
Nitric acid, phosphoric acid, etc. can be used. At this time, the amount of the inorganic acid used is not limited, but the subsequent coating film performance,
In particular, in order not to impair the water resistance, it is preferably in the range of 0.5 to 1.5 times the equivalent of the aliphatic sulfonate.

When the amount is less than 0.5 times the equivalent, unreacted aliphatic sulfonate remains, and when the amount exceeds 1.5 times the equivalent, the aliphatic sulfonate is not sodium- or potassium-free. In any case, the water resistance of the coating film is deteriorated, which is not preferable. The conditions for sodium removal or potassium removal can be quantitatively performed at room temperature according to a conventional method.

Other acid catalysts include organic carboxylic acids such as maleic acid and phthalic acid, carboxylic acids inherent in polyols, and phosphate-based catalysts, all of which have a weak action as acid catalysts. When combined with a toluenesulfonamide-modified melamine resin, the effect of accelerating the crosslinking reaction for forming the hexagonal pattern is weak. Even if unblocked sulfonic acid is used, a hexagonal pattern cannot be obtained.

Examples of the amine compound having a secondary amino group having a boiling point of 80 to 250 ° C. which serves as a blocking agent include, for example, di-2-ethylhexylamine, di-secondary butylamine, diallylamine, N-methylhexylamine, 3
-Pipecoline, 4-pipecoline, 2,4-lupetidine,
2,6-Lupetidine, 3,5-Lupetidine, morpholine, N-methylbenzylamine; examples of the amine compound having a tertiary amino group include N-methylmorpholine,
Triethylamine, tributylamine, N, N-dimethylallylamine, N-methyldiallylamine, triallylamine, N, N, N ', N'-tetramethyl-1,2
-Diaminoethane, N, N, N ', N'-tetramethyl-1,3-diaminopropane, N, N, N', N'-tetraallyl-1,4-diaminobutane, N-methylpiperidine, pyridine, 4-ethylpyridine, tripropylamine, N-pyropyrdiallylamine, 3-dimethylaminopropanol, 2-ethylpyrazine, 2,3-dimethylpyrazine, 2,5-dimethylpyrazine, 2,4-lutidine, 2,5- Lutidine, 3,4-lutidine, 3,5
-Lutidine, 2,4,6-collidine, 2-methyl-4-
Ethyl pyridine, 2-methyl-5-ethyl pyridine,
N, N, N ', N'-tetramethylhexamethylenediamine, N-ethyl-3-hydroxypiperidine, 3-methyl-4-ethylpyridine, 3-ethyl-4-methylpyridine, 4- (5-nonyl) Pyridine; Examples of the amine compound having a secondary and tertiary amino group include imidazole and N-methylpiperazine.
One kind or a mixture of two or more kinds.

When the boiling point of the blocking agent is less than 80 ° C., the blocking agent dissociates too quickly and foaming of the coating film occurs, and a three-dimensional turtle shell pattern cannot be obtained. Dissociation is too slow to get a tortoiseshell pattern.

The production of the blocked sulfonic acid compound is 2
The amine compound having a secondary or tertiary amino group and sulfonic acid are charged into a container and stirred at 20 to 30 ° C. for 10 to 20 minutes.

The mixing ratio of amine compound / sulfonic acid is 0.5 to 2, preferably 0.8 to 1.5 in terms of molar ratio, and only in this case, a beautiful three-dimensional turtle shell pattern is formed. . If the molar ratio of amine compound / sulfonic acid is less than 0.5, there are many sulfonic acids that are not blocked, so the curing reaction proceeds from low temperature during baking and a three-dimensional hexagonal pattern does not form. If the ratio exceeds 2, no improvement due to the addition of the blocking agent is observed, and the corrosion resistance of the obtained coating film decreases.

The mixing ratio of each component is (A) component 60 to 9
5 parts by weight, preferably 65 to 94 parts by weight, and 5 parts by weight to 40 parts by weight, preferably 6 to 35 parts by weight of the component (B), 100 parts by weight of the component (C) as a sulfonic acid is 0.1. It is 1 to 3 parts by weight, preferably 0.2 to 2 parts by weight.

When the amount of the component (A) used is less than 60 parts by weight, the coating film is brittle, and it is difficult to obtain a three-dimensional effect due to fluctuations in the baking conditions, and when it exceeds 95 parts by weight, sufficient crosslinking is achieved. Is not performed, and it becomes difficult to form a three-dimensional turtle shell pattern.

When the amount of the component (B) used is less than 5 parts by weight, sufficient crosslinking is not carried out, and a three-dimensional turtle shell pattern is less likely to occur. When it exceeds 40 parts by weight, the coating film is brittle and the baking conditions are high. It is difficult to obtain a three-dimensional tortoise shell pattern due to the sway.

If the amount of component (C) used is less than 0.1 parts by weight, the catalytic effect during baking is insufficient, and a three-dimensional turtle shell pattern is not formed. On the other hand, if it exceeds 3 parts by weight, the reaction is too fast and cracking occurs, and there is no three-dimensional effect, and sufficient corrosion resistance cannot be obtained.

The powder coating composition of the present invention includes the above (A)
In addition to the essential components of (C), coloring pigments such as titanium dioxide, red iron oxide, yellow iron oxide, inorganic pigments such as carbon black, phthalocyanine blue, phthalocyanine green, quinacridone red pigment, isoindolinone yellow pigment, etc. Organic pigments; metal powders such as aluminum powder and copper powder; talc, barium sulfate, silica, calcium carbonate,
An extender pigment such as alumina white or clay; mica powder or the like may be added. Further, in both the case of the clear powder paint and the colored powder paint, a thermoplastic resin such as a fluororesin, a vinyl copolymer resin, a polyethylene resin, a polypropylene resin, a polyester resin which does not contain a hydroxyl group can be added.

These pigments, metal powders, thermoplastic resins and the like are added to 40 parts by weight of the powder coating composition of the present invention.
It is preferably less than part by weight and can be used as a pattern adjusting agent for adjusting the size of a hexagonal pattern. If the amount of these used exceeds 40 parts by weight, the corrosion resistance of the coating film decreases.

In addition to the powder coating composition of the present invention, additives such as a leveling agent, a pigment dispersant, an ultraviolet absorber, a light stabilizer, a heat stabilizer and an antifoaming agent may be added if necessary. You can also Also, by adding a silicone resin-based additive,
By intentionally flipping the coating film, it is possible to add a hammer-tone tone and a tortoiseshell pattern.

Usually, the powder coating is mainly applied by the electrostatic spraying method, and therefore the particle diameter of the powder coating composition of the present invention is 15 from the viewpoint of coating workability (coating efficiency, throwing power).
It is desirable that the mesh be 0 mesh or less.

As the base material for coating the powder coating composition of the present invention, any material can be used as long as it can withstand the baking conditions described later, but an iron plate having a thickness of about 0.2 to 2 mm, a galvanized plate A metal plate such as a steel plate, an aluminum plate and a stainless plate is preferable.

To apply the powder coating composition of the present invention,
A commercially available electrostatic coating machine (load voltage -50
~ -90kV) or even after powder coating, etc., 150 ~ in hot air baking furnace, infrared furnace, induction heating furnace, etc.
300 ° C, preferably 160 to 250 ° C for 20 seconds to 60
Bake for 20 minutes, preferably 30 seconds to 30 minutes
The coating thickness is 00 μm, preferably 30 to 100 μm. By coating in this manner, a turtle shell-shaped coating film having excellent coating properties such as corrosion resistance and having a three-dimensional appearance and excellent design is formed.

The baking conditions are determined within the above range depending on the substrate (material to be coated) used. For example, when using an iron plate having a thickness of 0.5 mm, baking may be performed at 160 to 180 ° C. for 15 to 20 minutes. . If the coating thickness of the powder coating is less than 20 μm, it is not possible to obtain a sufficient three-dimensional turtle shell pattern,
When it exceeds m, a foaming phenomenon of the coating film occurs, and a beautiful turtle shell pattern cannot be obtained.

The coating film formed by baking the powder coating composition of the present invention has dense (fine) irregularities in a crepe pattern in a two-dimensional and unspecified direction, and the shape and the like are powder. It changes depending on the composition of the coating material, coating conditions, baking conditions, etc. By preparing these, a coating film having an arbitrary hexagonal pattern can be obtained.

FIG. 1 is a schematic plan view schematically showing a coated article formed from the powder coating composition of the present invention, and FIG. 2 is a schematic sectional view thereof.

In the figure, reference numeral 10 is a coated article, and a coating film 2 is formed on a base material 1. On the coating film 2, a high-profile, hexagonal irregular shaped mesh pattern 3 is formed almost uniformly on the entire surface of the coating film 2, and on the inner side thereof, dense dents and projections 4 having a crepe pattern are formed in unspecified directions. The hexagonal pattern is formed in a substantially uniform manner, is uniform and dense as a whole, and has a three-dimensional appearance and excellent designability.

A coated article having a coating film having such a hexagonal pattern has excellent designability and excellent coating film performance such as corrosion resistance. Therefore, the body and parts of automobiles; refrigerators, Home appliances such as washing machines and air conditioners; road materials such as poles, noise barriers and guardrails; building materials such as inner and outer walls of buildings, pillars, roofs, partition boards; electricity such as telephones,
Telecommunications equipment; pipes, fittings, metal machinery, waste bins, accessory cases, steel furniture, steel desks, beverage cans, iron, galvanized steel, stainless steel, aluminum and other metal products;
It can be used in the fields of glass, wood, gypsum board, woven fabrics made of glass fiber or the like, heat-resistant paper, plastics having a heat resistance of 150 ° C. or higher, and printed or colored products thereof.

Although the mechanism of the formation of the hexagonal pattern has not been sufficiently clarified, when the uncured coating film reaches a certain baking condition, the surface layer undergoes rapid surface hardening, which causes distortion in the surface layer and corrects it. Therefore, it is considered that a hexagonal pattern appears in the surface layer. In the present invention, in the presence of a sulfonic acid compound (blocked acid catalyst) blocked with a specific amine compound, a large amount of an alkoxy group (methoxy group) highly reactive with the hydroxyl group of the powder coating resin (A) is contained. It is presumed that by blending the toluenesulfonamide-modified melamine resin described above, a tortoiseshell pattern is generated due to such a rapid surface hardening during baking.

[0048]

As described above, according to the present invention, a specific toluenesulfonamide-modified melamine resin and a boiling point of 8 are used for a powder coating resin which has a specific hydroxyl group and is solid at room temperature.
Since the sulfonic acid compound blocked with the amine compound having a secondary or tertiary amino group at 0 to 250 ° C. is blended at a specific ratio, unlike the conventional uneven pattern,
It is possible to obtain a powder coating composition which is uniform and dense, gives a three-dimensional appearance and has an excellent design property and has excellent coating performance.

Further, according to the present invention, the above powder coating composition can be easily applied.

Further, according to the present invention, a coating film formed from the above powder coating composition is excellent in coating film performance, and is uniform and dense and has a three-dimensional effect unlike the conventional uneven pattern. A paint film having a hexagonal pattern having a certain excellent design property can be obtained, and a coated article having such a paint film can be obtained.

[0051]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. In the examples, parts are parts by weight and% is% by weight.
Indicates. Example 1 Almatex PD-8000 (trade name, solid content 100%) manufactured by Mitsui Toatsu Chemicals, Inc. based on the formulation shown in Table 1 7
5 parts, 25 parts of toluenesulfonamide modified melamine resin M-1 (trade name, solid content 100%) manufactured by Monsanto Chemical Co., and tripropylamine as a sulfonic acid blocked with a tertiary amine having a boiling point of 80 to 250 ° C. Blocked paratoluenesulfonic acid 2.0
Parts and weigh them uniformly with a dry blender (Mitsui Miike Kakoki Co., Ltd., trade name Henschel Mixer) for about 1 minute, and then extrude kneader (Bus Co., Ltd.) at a temperature condition of 80 to 100 ° C. Product name Busco Kneader PR-46)
Was melt-kneaded, and after cooling, finely pulverized with a hammer type impact pulverizer. Then, it was filtered through a wire mesh of 150 mesh to obtain a powder coating material.

The obtained powder coating is 0.5 mm × 100 m
Electrostatic coating is applied on an iron plate that has been treated with zinc phosphate of mx 200 mm and baked at 170 ° C for 20 minutes to give a coating film thickness of 50.
A coated plate of μm was obtained. A turtle shell pattern as shown in FIG. 1 was formed on the coated plate. The appearance of the obtained coated plate and the performance of the cured coating film are shown in Table 1.

Examples 2 to 10 and Comparative Examples 1 to 4 Examples 2 to 10 were prepared in the same manner as in Example 1 based on the formulations of Examples 2 to 10 and Comparative Examples 1 to 4 in Table 1 and Table 2. The powder coating materials of Comparative Examples 1 to 4 were obtained. Obtained Examples 2-1
0, powder coatings of Comparative Examples 1 to 4 were applied on a 0.5 mm × 100 mm × 200 mm zinc phosphate-treated iron plate in the same manner as in Example 1, and Examples 2, 6 to 10 were compared. Examples 1 to 4 are 170 ° C. for 20 minutes, and Examples 3 to 5 are 180 ° C.
After baking for 20 minutes, a coated plate having a coating film thickness of 50 μm was obtained. The appearance of each of the obtained coated plates and the performance of the cured coating film are shown in Tables 1 and 2.

In Table 1, Examples 1 and 2 are examples in which the kind of the acrylic resin for the powder coating containing the hydroxyl group as the component (A) and the ratio with the toluenesulfonamide-modified melamine resin as the component (B) were changed. And Examples 3 to 9 are (A)
Example 10 is an example in which the type of the polyester resin for the powder coating material containing the hydroxyl group of the component, the ratio of the toluenesulfonamide-modified melamine resin of the component (B), the type and the pattern adjusting agent are changed, and Example 10 is the component (A). This is an example in which a fluororesin is used as a resin for a powder coating material containing a hydroxyl group.

[0055]

[Table 1]

[0056]

[Table 2]

Footnotes to Tables 1 and 2 1) Mitsui Toatsu Chemical Co., Ltd., trade name, acrylic resin, hydroxyl value = 87 mg KOH / g, solid content = 100%, Tg
= 65 ° C. 2) S. C. Product name, acrylic resin, manufactured by Johnson, hydroxyl value = 94 mg KOH / g, solid content = 100
%, Tg = 50 ° C. 3) Nippon Ester Co., Ltd., trade name, polyester resin, hydroxyl value = 29 mg KOH / g, solid content = 100
%, Tg = 63 ° C. 4) CARGILL, trade name, polyester resin,
Hydroxyl value = 295 mg KOH / g, solid content = 100%,
Tg = 44 ° C. 5) Hitachi Chemical Co., Ltd., trade name, polyester resin, hydroxyl value = 100 mg KOH / g, solid content = 100
%, Tg = 58 ° C. 6) Asahi Glass Co., Ltd., trade name, fluororesin, hydroxyl value =
52 mgKOH / g, solid content = 100%, Tg = 60 ° C. 7) manufactured by Monsanto Chemical Co., trade name, toluenesulfonamide-modified melamine resin, Mn =
1340, Mw / Mn = 5.7, equivalent weight = 180 g / e
q, solid content = 100%, Tg = 42.3 ° C. 8) manufactured by Monsanto Chemical Co., trade name, toluenesulfonamide-modified melamine resin, Mn =
1023, Mw / Mn = 2.5, equivalent weight = 158 g / e
q, solid content = 100%, Tg = 40.4 ° C. 9) manufactured by Monsanto Chemical Co., trade name, toluenesulfonamide-modified melamine resin, Mn =
896, Mw / Mn = 2.0, equivalent weight = 151 g / eq,
Solid content = 100%, Tg = 36.8 ° C. 10) Tripropylamine blocked paratoluenesulfonic acid, tripropylamine / paratoluenesulfonic acid = 1/1 (molar ratio), tripropylamine boiling point = 1
56.5 ° C 11) Hoechst 9205 (trademark), tetrafluorocarbon manufactured by Hoechst 12) Parts by weight based on 100 parts by weight of resin and curing agent 13) Visual judgment Good: A hexagonal pattern was formed on the entire surface Defect: A hexagonal pattern was formed on the entire surface Did not occur at all. 14) Visual judgment Good: There is a three-dimensional effect Poor: There is no three-dimensional effect 15) JIS K-5400 (1990) 9.1 Based on salt spray resistance. Good: No rust or blisters on the coating Bad: Rust or blistering on the coating

As is clear from Tables 1 and 2, Examples 1 to 10 give a good hexagonal pattern and three-dimensional appearance, and also have excellent corrosion resistance, while the toluenesulfonamide-modified melamine resin is less than 5 Comparative Example 1 and Comparative Example 2 in which the toluenesulfonamide-modified melamine resin exceeds 40 parts by weight did not give a hexagonal pattern and a three-dimensional effect, and the corrosion resistance was poor. Comparative Example 3 in which the amount of the blocked acid catalyst was less than 0.1 parts by weight did not give a hexagonal pattern and a three-dimensional effect, and Comparative Example 4 in which the amount of the blocked acid catalyst exceeded 3 parts by weight did not give a three-dimensional effect. Moreover, the corrosion resistance was poor.

[Brief description of drawings]

FIG. 1 is a schematic plan view schematically showing a coated article formed from the powder coating composition of the present invention.

FIG. 2 is a schematic cross-sectional view of the coated article of FIG.

[Explanation of symbols]

 1 base material 2 coating film 3 irregular mesh pattern 4 dense unevenness 10 coated object

Claims (4)

[Claims] 1. (A) Hydroxyl value is 10 to 320 mg KO
100 parts by weight of a mixture comprising 60 to 95 parts by weight of a resin for powder coating which is solid at room temperature of H / g and (B) 5 to 40 parts by weight of a toluenesulfonamide-modified melamine resin having a glass transition temperature of 30 to 70 ° C. On the other hand, (C) a hexagonal pattern characterized by containing 0.1 to 3 parts by weight of a sulfonic acid compound blocked with an amine compound having a secondary or tertiary amino group having a boiling point of 80 to 250 ° C. as a sulfonic acid. A powder coating composition to give. 2. After applying the powder coating composition according to claim 1 on a substrate, it is maintained at a temperature of 150 to 300 ° C. for 20 seconds to 60.
The coating method of the powder coating composition according to claim 1, wherein the coating film is baked for a minute to form a coating film having a thickness of 20 to 200 µm. 3. The powder coating composition according to claim 1 is applied onto a substrate and then at a temperature of 150 to 300 ° C. for 20 seconds to 60 seconds.
A coating film formed from the powder coating composition according to claim 1, which is formed by baking for minutes and has a thickness of 20 to 200 µm. 4. The powder coating composition according to claim 1 is applied onto a substrate and then at a temperature of 150 to 300 ° C. for 20 seconds to 60.
A coated article having a coating film formed from the powder coating composition according to claim 1, which has a coating film having a thickness of 20 to 200 µm formed by baking for minutes.