JP2769679B2 - Painted metal plate and method of manufacturing coated metal plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated metal plate and a method for manufacturing a coated metal plate. More specifically, the present invention provides
The present invention relates to a coated metal plate which forms a concavo-convex pattern on the surface of an object to be coated, and is excellent in finish feeling and coating film performance, and a method for manufacturing a coated metal plate.

[0002]

2. Description of the Related Art Hammer tone paints have been used as one of the coating methods for finishing the surface of a workpiece in an uneven pattern. It is called a hammer tone paint because it forms a uniform pattern as if the metal surface was hit with a hammer. The hammer tone finish has the advantage that the finished pattern is beautiful and the coating performance is excellent in adhesion to the substrate, hardness, abrasion resistance, scratch resistance, etc. doing. As the application field of the hammer tone paint, it is also used for relatively small items such as sewing machines, air conditioners, stoves, and audio equipment, as well as shutters, outer wall materials, and pre-coated metal. Conventionally, a hammer tone pattern appears due to the action of silicone oil after a few minutes when an appropriate amount of silicone oil is added to the paint and applied to the surface of the object to be coated, and this is dried as it is to complete the hammer tone finish. Paints are known. However, the conventional hammer tone paint to which silicone oil is added, when mixed with other paints, may cause defects such as repelling and dents. Therefore, the production of hammer-tone paint to which silicone oil is added requires special equipment, and even at a painting site, the hammer-tone paint adheres to the surface of an object to be coated with another type of paint. Care must be taken to prevent the hammer tone paint from being mixed with other paints. Furthermore, when you apply other paints on the surface where the conventional hammer tone paint is painted,
There is also a drawback that the same coating failure phenomenon as described above occurs due to the influence of silicone oil.

[0003]

DISCLOSURE OF THE INVENTION The present invention is intended to provide a coating film which does not use silicone oil as in the case of conventional hammer tone paints, and has properties such as adhesion to a substrate, hardness, abrasion resistance and scratch resistance. Another object of the present invention is to provide a coated metal plate excellent in finish feeling and a method for manufacturing the coated metal plate.

[0004]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, by combining an undercoating film having a small surface tension and an overcoating material having a large surface tension, the appearance has been improved. It has been found that a coated metal sheet having excellent coating film performance can be obtained, and the present invention has been completed based on the findings. That is, the present invention provides (1) a heating residue of a resin consisting of 50 to 90% by weight of a component (A) polyester resin having a hydroxyl group and 50 to 10% by weight of a component (B) melamine resin on a metal plate surface.
An undercoat based on a mixture obtained by adding 2 to 8 parts by weight of the component (C) acrylic polymer to the parts by weight is applied and baked to form an undercoat, and then the component (D) has a hydroxyl value of 25. -80 mgKOH / g, number average molecular weight 1000-6
Topcoat having a surface tension of 30 to 40 dyne / cm, comprising 50 to 80% by weight of a polyester resin having a hydroxyl group having an acid value of 5 to 15 mg KOH / g and 50 to 20% by weight of a component (E) methylated melamine resin. A coated metal plate wherein a paint is applied and baked to form a top coat; and (2) 50-90% by weight of a component (A) polyester resin having a hydroxyl group on the surface of the metal plate; B)
Component (C) acrylic polymer 2 based on 100 parts by weight of the heating residue of a resin composed of 50 to 10% by weight of melamine resin
An undercoat based on the mixture to which ベ ー ス 8 parts by weight has been added is applied and baked to form an undercoat, after which the component (D) has a hydroxyl value of 25 to 80 mgKOH / g and a number average molecular weight of 1
000 to 6000, 50 to 80% by weight of a hydroxyl-containing polyester resin having an acid value of 5 to 15 mg KOH / g, and 50 to 20% by weight of a component (E) methylated melamine resin, having a surface tension of 30 to 40 dyne / cm. It is intended to provide a method for producing a coated metal sheet, characterized in that a top coat is applied and baked to form a top coat.

[0005] The plate to be coated in the present invention is a metal plate such as a steel plate, an aluminum plate, a steel plate plated with zinc or aluminum, and a steel plate plated with an alloy thereof. In the present invention, a polyester resin having a hydroxyl group and capable of being crosslinked with a melamine resin by a dehydration reaction is used as the component (A) of the undercoat paint. Examples of such a polyester resin include Becolite M-6402-50 [trade name, manufactured by Dainippon Ink Co., Ltd.] and Byron GK13CS [trade name, manufactured by Toyobo Co., Ltd.]. In the present invention, the melamine resin used as the component (B) of the undercoat paint may be any one that can be cured by a crosslinking reaction with the polyester resin at a low temperature and in a short time at the time of baking. The melamine resin used in the above can be used. Examples of such a melamine resin include a methylated melamine resin, a butylated melamine resin, a mixed alkylated melamine resin, and the like. In the present invention, the mixing ratio of the polyester resin of the component (A) and the melamine resin of the component (B) is as follows:
The heating residue is 50 to 90% by weight of the polyester resin and 50 to 10% by weight of the melamine resin. If the blending amount of the polyester resin is less than 50% by weight, the moldability of the coating film is undesirably reduced. On the other hand, if the blending amount of the polyester resin exceeds 90% by weight, the hardness of the coating film decreases, which is not preferable. In the present invention, an acrylic polymer is blended as the component (C) in the undercoat paint. The acrylic polymer has an effect of lowering the surface tension of the undercoat film, and is commercially available as a leveling agent, for example, Polyflow S, Polyflow No. 85 [both are manufactured by Kyoeisha Yushi Kagaku Kogyo Co., Ltd. ),
Trade name], Disparon L-1980-50, Disparon L-1984-50 [all manufactured by Kusumoto Kasei Co., Ltd.
[Product Name] can be suitably used. In the present invention, the acrylic polymer of the component (C) comprises the component (A)
2 to 8 parts by weight are blended with respect to 100 parts by weight of the heating residue of the polyester resin and the melamine resin of the component (B). The amount of the acrylic polymer is 2 parts by weight based on 100 parts by weight of the heating residue of the resin of the component (A) and the resin of the component (B).
If the amount is less than part by weight, the surface tension of the undercoat film is not sufficiently reduced, and a film having a good hammer tone cannot be obtained. If the blending amount of the acrylic polymer exceeds 8 parts by weight with respect to 100 parts by weight of the heating residue of the resin of the component (A) and the component (B), the coating performance of the undercoat coating film is unpreferably reduced. . In the present invention, as the component (D) of the top coat, a hydroxyl value of 25 to 80 mgKOH /
g, number average molecular weight 1000-6000, acid value 5-15 mg
A polyester resin having a hydroxyl group of KOH / g is used. Such a polyester resin can be obtained by condensation-polymerizing a polyhydric alcohol and a polybasic acid at 220 to 280 ° C. The equivalent ratio of the OH group of the polyhydric alcohol to the COOH group of the polybasic acid is preferably from 1: 1 to 5: 1.

In the present invention, the polyhydric alcohol used for producing the polyester resin as the component (D) includes, for example, ethylene glycol, propylene glycol, butylene glycol, 1,5-pentanediol,
1,6-hexanediol, neopentyl glycol,
Examples thereof include diethylene glycol, triethylene glycol, glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, and sorbitol. These polyhydric alcohols can be used alone or as a mixture of two or more. Can be used. In the present invention, the polybasic acid used for producing the polyester resin as the component (D) includes, for example, aliphatic polybasic acids such as maleic acid, fumaric acid, succinic acid, glutaric acid, adipic acid and sebacic acid; Aromatic polybasic acids such as phthalic acid, isophthalic acid, terephthalic acid and trimellitic acid can be mentioned. One of these polybasic acids can be used, or two or more can be used as a mixture. Further, in the present invention, an acid anhydride such as phthalic anhydride can be used as the polybasic acid. When an acid anhydride is used, its COOH equivalent is calculated as the acid anhydride being hydrolyzed to free COOH groups. In the present invention, the polyester resin used as the component (D) has a hydroxyl value of 25 to 80 mgKOH / g, preferably 40 mgKOH / g.
６０60 mgKOH / g and a number average molecular weight of 1000-6
000, preferably 3000 to 5000, and an acid value of 5 to 15 mgKOH / g, preferably 8 to 13 mgKOH / g. If the hydroxyl value of the polyester resin is less than 25 mgKOH / g, the crosslinking density of the coating film is insufficient, and a coating film having good performance cannot be obtained, which is not preferable. If the hydroxyl value of the polyester resin exceeds 80 mgKOH / g, the water resistance of the coating film is undesirably reduced. If the number average molecular weight of the polyester resin is less than 1,000, the strength of the coating film may be undesirably reduced. When the number average molecular weight of the polyester resin exceeds 6000, the viscosity of the coating material becomes high, and the coating workability is undesirably reduced. If the acid value of the polyester resin is less than 5 mgKOH / g, the storage stability of the coating material is undesirably reduced. If the acid value of the polyester resin exceeds 15 mgKOH / g, the durability of the coating film is undesirably reduced. In the present invention, the methylated melamine resin used as the component (E) is a melamine resin having a high surface tension and a low molecular weight region. Examples of such a melamine resin include Cymel 303.
[Mitsui Toatsu Chemical Co., Ltd. product name], Sumimar M40S
[Trade name, manufactured by Sumitomo Chemical Co., Ltd.]. In the present invention, the mixing ratio of the polyester resin of the component (D) and the methylated melamine resin of the component (E) is as follows:
The heating residue is 50 to 80% by weight of the polyester resin and 50 to 20% by weight of the methylated melamine resin. If the blending amount of the polyester resin is less than 50% by weight, the moldability of the coating film is undesirably reduced. On the other hand, when the blending amount of the polyester resin exceeds 80% by weight, the surface tension of the coating system is lowered, and a stable appearance cannot be obtained, which is not preferable.

[0007] The surface tension of the top coating composition used in the present invention comprising the polyester resin of the component (D) and the methylated melamine resin of the component (E) has a surface tension of 30 to 40 dyne / c.
m, more preferably 32 to 37 dyne / cm.
If the surface tension of the overcoat is less than 30 dyne / cm, it is not preferable because a hammer tone with excellent appearance cannot be obtained. The surface tension of the top coat is 40 dyne / c
If it exceeds m, the coating workability is undesirably reduced. In the hammer tone paint used in the present invention, a pigment, a dye, a solvent, and a pigment commonly used for paints may be added to the undercoat paint comprising the components (A), (B) and (C), if necessary. Additives and the like can be blended. In addition, pigments generally used for coatings are used in the topcoating composition comprising components (D) and (E).
Dyes, solvents, additives and the like can be blended. As the pigment to be blended in the undercoat paint and the topcoat paint used in the present invention, it is possible to use a coloring pigment, an extender pigment, and the like.Examples of such a pigment include aluminum paste, pearl pigment, titanium oxide, and carbon dioxide. Black, red iron, silica, mica, calcium carbonate and the like can be mentioned. The amount of the pigment is not particularly limited, and can be determined in consideration of the desired appearance of the coating film, the viscosity of the coating, the workability of coating, and the like. Examples of the additives to be added to the top coat used in the present invention include a pigment dispersant and an anti-scratch agent. It is effective to add 0.3 to 4% by weight of a fluororesin powder such as a polytetrafluoroethylene resin powder having a melting point of 300 ° C. or more to the paint as an anti-scratch agent. As the fluororesin powder, other than the above-mentioned polytetrafluoroethylene, a fluororesin powder such as polychlorotrifluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, or polyvinylidene fluoride can be used. If the amount of the fluororesin powder is less than 0.3% by weight, sufficient anti-scratch property cannot be obtained. No improvement in effect can be obtained. As such a fluororesin powder for preventing scratching, for example, Fostaflon TF-9205 [Hoechst Japan K.K., trade name] and the like can be suitably used. As a method for preparing the hammer tone paint used in the present invention, a usual method for producing a paint can be applied. An example of the preparation method is described below, but the preparation method of the paint used in the present invention is not limited to this. That is, the undercoat paint is polyester resin, melamine resin,
The solvent and the pigment are mixed, and the pigment particles are dispersed to 20 μm or less using a sand mill, an attritor, a roll mill, or the like. However, when the pigment is only the aluminum paste or the pearl pigment, only stirring by a disper is sufficient. Next, the acrylic polymer of the component (C) was mixed and sufficiently dispersed,
Subsequently, it can be prepared by adding an aluminum paste, an additive and the like, and stirring and mixing with a disper. As the coating method used in the present invention, spray coating, electrostatic coating, roller coating, and the like are possible. The top coat can be prepared and painted in the same manner.

[0008]

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. Examples 1 to 8, Comparative Examples 1 to 5 and Reference Example 1 (Preparation of paint) According to the composition shown in Table 1, component (A)
After mixing and dispersing the polyester resin, the melamine resin of component (B), the pigment and the solvent, the acrylic polymer of component (C) was mixed and sufficiently dispersed. Next, the additives were added, and the mixture was stirred and mixed with a disper to prepare 13 types of 14 undercoat paints. Further, according to the composition shown in Table 1, the polyester resin of the component (D), the methylated melamine resin of the component (E), the pigment and the solvent are mixed and dispersed,
Further, in Reference Example 1, five types of silicone oil were added,
Four top coats were prepared.

[0009]

[Table 1]

[0010]

[Table 2]

[Note] 1) Polyester resin 1: Beccolite M-6402-
50 [manufactured by Dainippon Ink and Chemicals, Inc., trade name: hydroxyl value 55 mgKOH / g, number average molecular weight 2800, acid value 7.5 mgKO
H / g, heating residue 50% by weight xylene solution] 2) Polyester resin 2: Byron GK13CS [manufactured by Toyobo Co., Ltd., trade name: hydroxyl value 45 mgKOH / g, number average molecular weight 6500, acid value 3 mgKOH / g, heating 3) Melamine resin: Cymel 325 [trade name: methylolated melamine resin, manufactured by Mitsui Cyanamid Co., Ltd., heated residue 60% by weight n-butanol solution] 4) Acrylic polymer 1: Polyflow S [manufactured by Kyoeisha Yushi Kagaku Kogyo Co., Ltd.] 5) Acrylic polymer 2: Dispalon L-1980-
50 [Kusumoto Kasei Co., Ltd., trade name] 6) Polyester resin: oil-free polyester resin [Nippon Oil & Fat Co., Ltd., trade name] (hydroxyl value 70 mgKOH /
g, number average molecular weight 2200, acid value 8 mg KOH / g) 7) Melamine resin: Sumimar M40S [Sumitomo Chemical Co., Ltd.
8) Scratch inhibitor: Fostaflon TF9205 [trade name, manufactured by Hoechst Japan Co., Ltd.] 9) Solvesso # 200: aromatic hydrocarbon [trade name, manufactured by Shell Chemical Co., Ltd.] 10) Silicone oil: Silicone TRS10N [trade name, manufactured by Hoechst Japan Co., Ltd.] (Preparation of test piece) As a coated plate to be used, a chemically treated galvanized steel sheet having a thickness of 0.4 mm was used. . As a coating method, first, an undercoat paint of Table 1 was applied using a bar coater # 20 so that the dry coating film thickness became 20 μm, and was heated and dried at an ultimate plate temperature of 210 ° C. for 30 seconds.
Next, the top coat of Table 1 was applied using a bar coater # 14 so that the dry coating film thickness became 10 μm, and dried at an ultimate plate temperature of 230 ° C. for 30 seconds to prepare a test piece. A test was performed on the prepared test piece according to the test method described below. The results are shown in Table 2.

[0012]

[Table 3]

[0013]

[Table 4]

(1) Appearance of paint film The finish of the painted surface is visually observed, and the hammer tone pattern of the painted surface is higher than that of the conventional paint of Reference Example 1 ◎, equivalents are ○, inferior are x. (2) In a room with a pencil hardness of 20 ° C, JIS K 5400 (1990)
Perform the test in accordance with 8.4.2, and pass those that are harder than H. (3) Adhesiveness First, apply JIS K 5400 to a test specimen in a room at 20 ° C.
(1990) A cross-cut is made with a cutter knife according to 8.5.1 (cross-cut method), and an Erichsen tester [JIS K 5400 (1990)]
Extrude 6.0mm at [8.2 Erichsen value]. After that, the cellophane adhesive tape was sufficiently adhered on the grid, and the cellophane tape was immediately peeled off instantaneously in the direction perpendicular to the surface of the coating film. Are rejected. (4) Workability In a room at 20 ° C., the same coated plate as the test piece (1T) to 6 sheets (6
T) is sandwiched and tightened with a vise to perform 180 ° close contact bending. The bending tip is observed with a 10-fold loupe, and indicates the processing level at which crack-free processing is performed. 1T to 4T are considered acceptable. (5) Impact resistance In a room at 20 ° C, JIS K 5400 (1990)
The test is carried out according to 8.3.2 (Dupont type, weight 1kg, height 50cm). Thereafter, a cellophane adhesive tape is sufficiently adhered to the test portion of the coating surface, and the cellophane tape is immediately peeled off instantaneously in a direction perpendicular to the coating film surface, and the state of peeling is examined. A state in which it was completely removed without being peeled was considered as a pass. (6) Scratch resistance In a room at 20 ° C, surface property tester HEIDON-14S
Using [Shinto Kagaku Co., Ltd.], the test pieces were rubbed 100 times reciprocally at a weight of 833 g / in ² , a moving speed of 5000 mm / min, and a moving width of 5 cm. Is observed and evaluated according to the following. A: No damage at all. ：: Slight scratch is observed. Δ: Scratches are observed. ×: Scratch was severe or hammer tone pattern was shaved. As is clear from the results in Table 2, Examples 1 to 5 of the present invention were used.
The test piece coated with the paint of No. 8 has a good coated surface condition and shows satisfactory results in any of pencil hardness, adhesion, workability, impact resistance and scratch resistance, and is a conventional hammer tone paint. Even when compared with the test piece coated with the coating material of Reference Example 1, it can be seen that the mechanical performance of the coating film is equivalent and the appearance of the coating film is excellent. The test piece to which the paint of Comparative Example 1 in which the amount of the polyester resin in the undercoat paint was small was applied had poor adhesion. The test piece to which the paint of Comparative Example 2 was applied in which the amount of the polyester resin in the undercoat paint was too large was inferior in scratch resistance. The test piece to which the paint of Comparative Example 3 in which the amount of the acrylic polymer in the undercoat paint was small was applied was inferior in the appearance of the paint film. The test piece to which the paint of Comparative Example 4 was applied, in which the amount of the acrylic polymer in the undercoat paint was too large, was similarly poor in the appearance of the paint film. The test piece to which the coating material of Comparative Example 5 in which the amount of the melamine resin in the top coating material was small was applied was inferior in the appearance of the coating film and the scratch resistance. As described above, the test pieces coated with the paints of the respective comparative examples deviating from the present invention showed unsatisfactory results in any of the test items. On the other hand, according to the method for producing a coated metal plate of the present invention, a coated metal plate having a beautiful uneven pattern formed on the surface of the object to be coated and having excellent finish feeling and coating film performance was obtained.

[0015]

According to the method for producing a coated metal plate of the present invention, since the coating does not contain silicone oil, it has an adverse effect on other coatings and causes coating defects such as cissing and dents. In addition, there is no need for special measures required in the conventional coating method using a hammer tone paint, for example, there is no need to isolate it from other paints in a paint production environment or a paint environment. Further, it has excellent coating film performance such as adhesion to a substrate, hardness, abrasion resistance, and scratch resistance, and has a better coating film appearance than a coated metal plate using a conventional hammer tone paint. Further, by adjusting the blending amount of the acrylic polymer of the component (C), it is possible to obtain a design that cannot be obtained by a conventional coating method using a hammer tone paint.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification code FI B05D 7/14 B05D 7/14 G 101 101A 7/24 302 7/24 302P 302S 302V (72) Inventor Akio Tashiro Osaka-shi, Osaka 4-1-1 Minamihonmachi, Chuo-ku Inside Yodogawa Steel Works, Ltd. (58) Field surveyed (Int.Cl. ⁶ , DB name) B05D 5/06 104 B05D 1/38 B05D 3/02 B05D 5/00 B05D 7 / 14 B05D 7/14 101 B05D 7/24 302

Claims (2)

(57) [Claims] 1. A heating residue of a resin comprising 50 to 90% by weight of a polyester resin having a hydroxyl group (A) and 50 to 10% by weight of a melamine resin (B) on the surface of a metal plate.
Component (C) acrylic polymer 2-8 based on 0 parts by weight
After applying and baking an undercoat based on the mixture to which parts by weight have been added to form an undercoat, component (D) a hydroxyl value of 25 to 80 mgKOH / g and a number average molecular weight of 1000 to 1000
6000, 50 to 80% by weight of a hydroxyl group-containing polyester resin having an acid value of 5 to 15 mg KOH / g and 50 to 20% by weight of a component (E) methylated melamine resin, and a top coat having a surface tension of 30 to 40 dyne / cm. A coated metal plate characterized by forming a top coat by applying a paint and baking. 2. A heating residue of a resin comprising 50 to 90% by weight of a component (A) polyester resin having a hydroxyl group and 50 to 10% by weight of a melamine resin (B) on the surface of a metal plate.
Component (C) acrylic polymer 2-8 based on 0 parts by weight
After applying and baking an undercoat based on the mixture to which parts by weight have been added to form an undercoat, component (D) a hydroxyl value of 25 to 80 mgKOH / g and a number average molecular weight of 1000 to 1000
6000, 50 to 80% by weight of a hydroxyl group-containing polyester resin having an acid value of 5 to 15 mg KOH / g and 50 to 20% by weight of a component (E) methylated melamine resin, and a top coat having a surface tension of 30 to 40 dyne / cm. A method for producing a coated metal sheet, comprising applying a paint and baking to form a top coat.