JP3365756B2 - Painted metal plate with excellent scratch resistance - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated metal sheet excellent in workability and in which scratches are inconspicuous and excellent in scratch resistance. 2. Description of the Related Art When a metal plate is subjected to clear coating, the surface state becomes smooth, high in glossiness and high in sharpness, a deep and beautiful appearance is obtained, and fingerprints and stains become inconspicuous. Therefore, it is used in various fields including building materials. However, they may be damaged during processing and construction, and require careful attention during handling. In addition, in a site that is easily damaged, such as a floor or a table top, the scratch resistance is insufficient and the device cannot be used. The scratch resistance of the coating is improved by the addition of inorganic aggregates. For example, fibrous glass or flaky glass is added to improve abrasion resistance and scratch resistance, or an inorganic resin having an average particle size of 3 to 30 μm is added to an acrylic resin paint as disclosed in JP-A-8-183926. Aggregate was added to the coating film in an amount of 5
A coated metal plate that imparts scratch resistance and stain resistance by adding 〜60 parts by weight is introduced. [0003] However, since the transparency of the coating film is poor in any of these, the design properties of the base metal and the undercoat coating film cannot be fully utilized. On the other hand, as a means for improving the scratch resistance and wear resistance, there is irradiation with an electron beam or the like. Since the coating film irradiated with the electron beam becomes hard with a pencil hardness of 9H or more, the above performance can be satisfied. However, the workability of the coating film is low, the weather resistance is inferior to that of the thermosetting coating film, expensive paint and irradiation equipment are required, and the production cost is high. The present invention, in order to solve such problems, by forming a clear coating film containing silica on the outermost layer, fully utilize the design properties of the underlying metal or undercoat coating film,
An object of the present invention is to provide a coated metal sheet having excellent wear resistance and scratch resistance. [0004] In order to achieve the object, the present invention is directed to a coated metal plate having a coating film formed on the surface of the metal plate, the silica having an average particle size of 0.5 to 8.0 µm. The resin solid
A clear coating film having a dry coating film thickness of 5 to 40 μm is formed on the outermost layer by a coating compounded in an amount of 1 to 2.5 % by weight per minute ,
The 60 ° gloss value of the coating was adjusted to 55 to 75.
Further, a triazine-based ultraviolet absorber and / or a benzotriazole-based ultraviolet absorber may be added to the paint for forming the outermost layer coating film. DETAILED DESCRIPTION OF THE INVENTION A coated metal plate according to the present invention has a clear coating film formed on the outermost layer, and the coating material may be polyvinyl alcohol, polyvinyl butyral, polyvinyl acetal, polyvinyl acetate, polyvinyl acetate, or the like. Vinyl resins such as vinyl chloride, polyvinylpyrrolidone and polystyrene; acrylate resins such as polymethyl (meth) acrylate, polybutyl (meth) acrylate, polyacrylamide and polyacrylonitrile; polyester resins; polycarbonate resins; polyurethane resins; polyamide resins and urea Resins, polycaprolactone resins, polyarylate resins, polysulfone resins, silicone polyester resins, epoxy resins, and the like, and copolymers or mixtures thereof are used. The coating material for forming the outermost layer coating film has an average particle size of 0.1.
5 to 8.0 μm silica is mixed in an amount of 1 to 2.5 % by weight.
If the average particle size of the silica is less than 0.5 μm, sufficient scratch resistance cannot be obtained when the pencil hardness of the coating film is F or less, and if it exceeds 8.0 μm, the adhesion of the coating film decreases, and the coated metal plate is bent. When this occurs, the coating film breaks and easily falls off. If the amount of silica is less than 1% by weight, sufficient scratch resistance cannot be obtained, and the 60-degree gloss value exceeds 75, so that the scratches become noticeable.
Conversely, if it exceeds 2.5 % by weight, the gloss value is less than 55 , so that the transparency is impaired and the design of the base is not sufficiently exhibited.
In addition, when the film is bent, the coating film is easily broken. [0007] The outermost layer coating film is formed by applying the above coating material by a known method so as to have a dry coating film thickness of 5 to 40 µm, followed by drying and baking. If the dry coating thickness is less than 5 μm, sufficient abrasion resistance cannot be obtained, and if it exceeds 40 μm, the solvent remaining in the coating film will vaporize rapidly during drying and baking, resulting in a pinhole called “side”. Coating film defects may occur. On the other hand, if the thickness of the dried coating film exceeds 40 μm, the transparency is impaired, and the design of the base is not sufficiently exhibited. The dry coating thickness is 10 to 25 μm from the balance of design and abrasion resistance.
Is preferred. [0008] The outermost layer coating film preferably has a pencil hardness of 2H or more. In applications such as flooring materials where wear is expected to decrease, methylated melamine, butylated melamine, urea and isocyanate are added to the coating to increase the coating film hardness. A curing catalyst such as a sulfonic acid compound may be added for curing in a short time. The material of the metal plate used as the base is not particularly limited, and a cold rolled steel plate, various plated steel plates, a stainless steel plate, a copper plate, an aluminum plate and the like can be used. Prior to the formation of the thermoplastic resin coating film, the base metal plate is subjected to a chemical conversion treatment such as mechanical polishing, pickling, phosphate treatment or chromate treatment, depending on the surface condition of the metal plate, and the coating film adhesion Can also be increased. The coated metal sheet according to the present invention may be provided with a clear coating directly on the surface of the metal sheet, and a base coat layer and / or a primer layer between the metal sheet base and the outermost clear coating layer. May be provided. Further, these base coat layers and primer layers may be colored, such as white, or colorless and transparent. The color tone of the clear coating film can be freely set, but it is desirable that the clearness is as high as possible in order to sufficiently express the design of the base. [0011] When an ultraviolet absorber is added to the outermost layer coating film, deterioration of the coating film adhesion and discoloration due to transmission of sunlight, ultraviolet rays and the like are suppressed. It is necessary that the ultraviolet absorber used has excellent heat resistance, sublimation resistance and solubility. Above all, the benzotriazole-based and triazine-based ultraviolet absorbers are excellent in heat resistance with a weight loss of 10% by weight or less at 300 ° C. under a heating condition (in air) at a heating rate of 5 ° C./min. The UV absorber to be added to the coating for forming the outermost layer coating film may be a benzotriazole-based or triazine-based alone or a mixture thereof. Further, a light stabilizer such as a hindered amine-based light stabilizer may be blended at a ratio of 3% by weight or less. The benzotriazole-based ultraviolet absorber includes
Octyl-3- [3-t-butyl-5- (2H-benzotriazol-2-yl) -4-hydroxyphenyl]
Propinate (TINUVIN 3 manufactured by Ciba Geigy)
84), 2- [2-hydroxy-3,5-bis (α,
α'dimethylbenzyl) phenyl] -2H-benzotriazole (TINUVIN 90 manufactured by Ciba-Geigy)
0), a condensate of methyl-3- [3-t-butyl-5- (2H-benzotriazol-2-yl) -4-hydroxyphenyl] propinate and polyethylene glycol (molecular weight: about 300) (TINUVI manufactured by Ciba Geigy)
N 1130), 2- [2'-hydroxy-3'-
(3 ", 4", 5 ", 6" -tetrahydrophthalimidomethyl) -5'-methylphenyl] -benzotriazole (Viosorb 590, manufactured by Kyodo Yakuhin). The triazine-based UV absorber includes 2- [4
-(2-hydroxy-3-didecyloxypropyl)-
Oxy] -2-hydroxyphenyl] -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine and 2- [4-[(2-hydroxy-3-tridecyloxypropyl)- Oxy] -2-hydroxyphenyl]
-4,6-bis (2,4-dimethylphenyl) -1,
3,5-Triazine mixture (TIBA Geigy Co., Ltd.
NUVIN 400). These ultraviolet absorbers may be used alone or in combination.
The amount of the ultraviolet absorber is 1 to the nonvolatile component of the paint.
It is preferable to adjust so as to be about 18% by weight. 1
If the amount is less than 18% by weight, the effect of addition is small. If the amount exceeds 18% by weight, stain resistance and workability of the coating film are liable to be deteriorated, and the appearance is impaired. [0014] The hindered amine light stabilizer is incorporated in an amount of 3% by weight or less based on the nonvolatile components of the paint, if necessary, in order to improve the light resistance of the outermost layer coating film. For example, bis (2,2,6,6-tetramethyl-4-piperidyl)
Sebacate (SANOL LS770 manufactured by Sankyo), bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate (SANOL LS76 manufactured by Sankyo)
5), 1- {2- [3- (3,5-di-t-butyl-4)
-Hydroxyphenyl) propionyloxy] ethyl
-4- [3- (3,5-Di-tert-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-
Tetramethylpiperidine (SANOL LS manufactured by Sankyo)
2626), 4-benzoyloxy-2,2,6,6-
Tetramethylpiperidine (SANOL LS manufactured by Sankyo)
744), 8-acetyl-3-dodecyl-7,7,
9,9-Tetramethyl-1,3,8-triazaspiro [4,5] decane-2,4-dione (SANKOH manufactured by Sankyo)
OL LS440), bis (1,2,2- (3,5-di-t-hydroxybenzyl) -2-n-butylmalonate)
2,6,6-pentamethyl-4-piperidyl) (TINUVIN 144, Ciba-Geigy), bis (2,2,6,6-tetramethyl-4-piperidyl) succinate (TINUVIN 780F, Ciba-Geigy)
F), a polycondensate of dimethyl succinate and 1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine (TINUV manufactured by Ciba Geigy)
IN 622LD), poly {[6- (1,1,3,3-
[Tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2
2,6,6-Tetramethyl-4-pyridyl) imino]} (CHIMASSRB 94 manufactured by Ciba-Geigy)
4LD), N, N′-bis (3-aminopropyl) ethylenediamine and 2,4-bis [N-butyl-N- (1,
Polycondensate of 2,2,6,6-pentamethyl-4-piperidyl) amino] -6-chloro-1,3,5-triazine (CHIMASSRB 119F manufactured by Ciba Geigy)
L), bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate (Tiba Geigy Co., Ltd.)
INUVIN 292), bis (1-octaoxy-
2,2,6,6-tetramethyl-4-piperidyl) sebacate (TINUVIN 12 manufactured by Ciba Geigy)
3), HA-70G (manufactured by Sankyo), Adekastab LA-
57, LA-62, LA-63, LA-67, LA-68, LA-82, LA-87 (manufactured by Asahi Denka Kogyo KK) These light stabilizers may be used alone or in combination of two or more. May be used in combination. When the compounding amount of the light stabilizer exceeds 3% by weight based on the coating non-volatile component, the effect of improving the light resistance is saturated, and the coating appearance is rather deteriorated. In order to effectively exert the light stabilizer, 0.5 to 1.5 times
It is preferable to set it to% by weight. Example 1 (Top layer) Coating in which a clear coating film is directly provided on a base metal plate
Manufacture of steel sheet (Examples 1 and 2 of the present invention, Comparative Examples 1 to 4 and 9 to 12 ) Stainless steel sheet (sheet thickness 0.5 mm, SUS304HL)
After performing degreasing, surface conditioning treatment, and coating type chromate treatment, silica having an average particle diameter of 0.3 to 12 μm
A transparent polyester resin paint containing 15% by weight and 3% by weight of a triazine-based UV absorber (TINUVIN 400 manufactured by Ciba Geigy) is applied so that the dry film thickness becomes 12 μm, and dried at a reached plate temperature of 230 ° C. for 1 minute. It was baked to form the outermost coating film. Clear via the base coat layer (outermost layer)
-Manufacture of coated steel sheet with coated film (Examples 3 and 4 of the present invention, Comparative Examples 5 to 8 and 13 to 16 ) For hot-dip galvanized steel sheet (sheet thickness 0.5 mm, adhesion amount per side 45 g / m ² ) After performing degreasing, surface conditioning treatment, and coating type chromate treatment, a black thermosetting polyester resin paint is applied so that the dry coating thickness becomes 15 μm,
Dry baking was performed at an ultimate plate temperature of 220 ° C. for 1 minute to form a black base coat layer. On top of this, an average particle size of 0.3 to 12 μm
A transparent polyester resin paint containing 0.5 to 15% by weight of silica and 3% by weight of a triazine-based UV absorber (TINUVIN 400 manufactured by Ciba Geigy) is applied so that the dry film thickness becomes 12 μm. It was dried and baked at a temperature of 230 ° C. for 1 minute to form an outermost layer coating film. Performance Test of Painted Steel Sheets For each of the obtained coated steel sheets, the coating film adhesion, pencil hardness,
Workability, abrasion resistance, gloss and paint appearance were investigated. In the coating film adhesion test, a cross section of Eriksen (JIS G 33
The test was performed by inserting a grid pattern specified in No. 20 and extruding 6 mm), and after applying a cellophane adhesive tape, the peeling state of the coating film was evaluated in the following five steps by forced peeling. 5: No peeling 4: Peeling number is within 10 out of 100 squares 3: 11 to 30 peeling out of 100 squares 2: 31 to 70 peeling out of 100 squares 1: 100 squares Among them, the number of peeling is 71 to 100. The pencil hardness is measured by a scratching method using Mitsubishi Uni (manufactured by Mitsubishi Pencil) in accordance with JIS K 5400. evaluated. In the workability test, the coating film surface was observed in a 180 ° bending process of 0 to 6 t (the number of sheets sandwiching the same plate thickness as the test piece) in a room at 20 ° C., and the state of occurrence of cracks was evaluated as follows. Usually, if the mark is ○ or more, it can be practically used for a precoated steel sheet. ◎: No cracks occurred at 0 to 2 t. ○: Cracks occurred at 3 to 4 t. △: Cracks occurred at 5 t. X: Cracks occurred at 6 t.
a 6mm diameter hole in the center of the test specimen
After the weight was measured, the test piece was attached to a Taber tester, rotated 200 times, and the weight of the test piece was measured. The weight loss between the test pieces before and after the test was determined, and the Taber index was calculated according to the following equation. It shows that the larger the numerical value of the Taber index is, the easier it is to wear. Taber index = abrasion loss (mg) × 1000 / rotational speed (200) The gloss was measured using a specular reflectivity measuring device, with the incident angle of light from the light source being 60 degrees and the reflection angle being 60 degrees. . The higher the value of the reflectance, the higher the glossiness. The appearance of the coating film was evaluated by the difference ΔL in whiteness (L value) based on the transparency of the coating film without silica. The lower the ΔL value, the higher the transparency. Table 1 shows the components of the outermost layer of each coated steel sheet and the test results. As is clear from Table 1, the coated steel sheets according to the present invention are all excellent in coating film performance,
Increasing the amount of silica increases the coating hardness,
There was a tendency for the abrasion resistance and transparency to decrease. On the other hand, the coated steel sheet of the comparative example had one of the performances of the respective coating films.
One or more were inferior. In other words, those with a small amount of silica had too high a glossiness to make the scratches more conspicuous, while those with a large amount of silica had a ΔL of 10 or more, resulting in poor transparency and poor workability. In addition, those having a small silica particle diameter had insufficient coating film hardness, and those having a large silica particle diameter were opaque and had poor abrasion resistance. [Table 1] Example 2: Forming a clear coating film (outermost layer) via a base coat layer
Of coated steel sheet (Examples 5 to 13 of the present invention and Comparative Examples 17 to 20 ) Degreasing, surface conditioning, and coating type chromate on hot-dip galvanized steel sheet (sheet thickness 0.5 mm, adhesion amount per side 45 g / m ² ) After performing the treatment, a black thermosetting polyester resin paint is applied so that the dry coating thickness becomes 15 μm,
Dry baking was performed at an ultimate plate temperature of 220 ° C. for 1 minute to form a black base coat layer. On top of this, a transparent polyester-based resin coating material in which the type and amount of the ultraviolet absorber was changed (in each coating material, 5% by weight of silica having an average particle size of 2.5 μm, and a hindered amine light stabilizer TINUVIN 123 were coated with a non-volatile coating material) 1.5% by weight per minute) and a dry coating thickness of 12
μm, and dried and baked at an ultimate plate temperature of 230 ° C. for 1 minute to form an outermost surface coating film. Each of the ultraviolet absorbers used was heated in the air at a temperature rising rate of 5 ° C./min and subjected to thermogravimetric analysis to determine the weight loss rate at 300 ° C. The weight loss rate of triazine-based (TIN
UVIN400), 3.5% by weight of benzotriazole type (TINUVIN384), 3% by weight of benzophenone type (Viosorb 130 manufactured by Kyodo Yakuhin).
It was 3.0% by weight, and it was confirmed that the triazine-based and benzotriazole-based ultraviolet absorbers were excellent in weather resistance and heat resistance. A test piece was cut out from each of the manufactured coated steel sheets and examined for light resistance. The light resistance test was carried out in a sunshine weather meter set at an atmosphere of 63 ° C. for 500 hours under a repetitive condition of 60 minutes of carbon arc irradiation and 12 minutes of fresh water injection. The color difference ΔE before and after the test was determined. Further, in the same manner as in Example 1, the coating film adhesion and workability were examined. Table 2 shows the test results of the outermost layer coating film by type and amount of the ultraviolet absorber. As can be seen from Table 2, the coated steel sheets according to the present invention all show excellent performance, and in particular, those in which triazine and benzotriazole are mixed in a ratio of 1 to 1 are more light-resistant than those in which each is blended alone. Was found to be excellent. On the other hand, those without an ultraviolet absorber or those with a benzophenone compound could not obtain sufficient light resistance. [Table 2] As described above, since the outermost layer of the coated metal plate of the present invention is a clear coating film, the design properties of the base metal plate and the undercoating film can be fully utilized, and the abrasion resistance can be improved. Because of its excellent scratch resistance, it can be applied to building materials, home appliances, kitchen equipment materials, and the like.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI C09D 7/12 C09D 7/12 Z 201/00 201/00 (56) References JP-A-4-317774 (JP, A) ( 58) Field surveyed (Int.Cl. ⁷ , DB name) C23C 28/00 B05D 7/14 B05D 7/24 302 B05D 7/24 303 C09D 5/00 C09D 7/12 C09D 201/00

Claims (1)

(1) A coated metal plate having a coating film formed on the surface of a metal plate, wherein silica having an average particle size of 0.5 to 8.0 μm is coated with a resin.
With a paint blended from 1 to 2.5 % by weight based on the solid content
A coated metal plate excellent in scratch resistance, wherein a clear coating film having a dry coating film thickness of 5 to 40 μm is formed on the outermost layer, and the coating film has a 60 ° gloss value of 55 to 75.